This paper expounds the theoretical points of Piaget, Vygotsky and Bruner respectively: Piaget's cognitive development theory: he first put forward the theory of cognitive structure and cognitive development stage. First, the stage theory of cognitive development. Each stage is a unified whole, not the sum of some isolated behavior patterns; Each stage has its main behavior pattern, which marks the behavior characteristics of this stage; There is no quantitative difference between stages; The behavior pattern of the previous stage is always integrated (or merged) into the next stage. Every behavior pattern originates from the structure of the previous stage. The former is the preparation of the latter and is replaced by the latter. The stages of children's cognitive development are not stepped, but overlap to some extent. The age of each cognitive development stage is different because of everyone's intelligence, motivation, practical and educational influence and social environment, and can be advanced or postponed. However, the order of stages remains unchanged and cannot be interchanged. Piaget divided children's cognitive development into four stages with different levels, namely, perception-movement stage (birth -2 years old), pre-operation stage (2-7 years old) and specific operation stage (7- 1 1 year old). Formal operation (from 1 1- 12 years old. According to Piaget's theory of stages of cognitive development, we should not go beyond the mature conditions of children and put forward too high and unrealistic requirements for children when conducting scientific education. Second, cognitive structure theory: cognitive development is an internal self-adjustment process in which individuals achieve a balanced state through assimilation and adaptation in order to solve cognitive conflicts in the environment. "Assimilation" refers to the individual's bringing the object into the schema of the subject, which causes the change of schema quantity. Third, the theory of knowledge classification: the acquisition of human knowledge is an active process. In order to understand things, we must incorporate physical objects into the transformation system. At the same time, acquiring knowledge also involves the transformation of physical objects to understand how a certain state is generated. Piaget believes that children will have two kinds of experiences when operating physical objects: physical experience and logical-quantitative experience, which form physical knowledge and quantitative logical knowledge respectively.

Vygotsky's point of view: Vygotsky is an outstanding psychologist in the Soviet Union. He put forward the concept of "zone of proximal development". Vygotsky put forward his own views on the development of the concept of children. He believes that the development of children's concept consists of three periods: conceptual ambiguity, compound thinking and abstract thinking. In his view, the concept of daily life is the concept of years gradually summed up according to the specific things in life, also known as spontaneous concept. Scientific concept refers to the concept that is constantly extended in the deduction of concept system. The biggest difference between scientific concepts and everyday concepts is that the former is systematic, while the latter lacks systematicness.

What are the implications of Piaget, Vygotsky and Bruner's theories for preschool children's science education? According to Piaget's theory of stages of cognitive development, we should not exceed the mature conditions of children and put forward too high and unrealistic requirements for children's age when conducting children's science education. We should encourage children to learn actively. For science education, we must pay attention to let children do more homework and use their brains, neither of which is needed. Children are active learners. They were not taught by others, but learned by themselves. Teachers should cherish children's natural curiosity and exploration spirit. In the process of thinking, children contact external things with their bodies and five senses, which enriches their experience and develops their cognitive ability. Children's cognitive structure and moral structure are different from those of adults. The new education law should make every effort to teach materials in a form suitable for children of different ages according to their cognitive structure and different stages of development. Educators should aim at children's reality, analyze the cognitive structure of different age stages, organize teaching materials and conduct teaching in advance according to different levels of teaching materials, which may enable children to learn some basic concepts in advance.

Vygotsky's enlightenment: we should pay great attention to enriching children's lives, encourage children to be active in different environments, and provide them with all kinds of analytical and comprehensive materials and opportunities to obtain them.

Bruner's revelation: Let children experience the emotion that scientists get from the process of discovery, so as to stimulate their learning motivation. Children can understand the nature of science through the process of "discovery" and form scientific knowledge.