The word quality is a physiological concept, which refers to people's innate physiological and anatomical characteristics, mainly referring to the characteristics of nervous system, brain, sensory organs and motor organs. Quality is the premise of the development of psychological activities. Without this material basis, psychological development is impossible. Different disciplines have different interpretations of quality, but they all have one thing in common, that is, quality is based on people's physical and psychological reality and on people's natural attributes. In other words, the difference of individual's physical and psychological maturity level determines the difference of individual's quality. Therefore, the understanding of people's quality should be based on people's physical and mental organizational structure and quality level.