All natural sciences come from practice, and are born on the basis of observing natural phenomena and summing up and developing in practice that conforms to scientific experiments. So is the development of physics. Physics (science) experiment is a scientific activity in which people artificially control, create or purify a natural process of growth according to the purpose of research, and make it develop according to the expected process, and at the same time observe and explore the changing law of physical process as far as possible without disturbing the objective state. It is very important in observation experiment. Scientific observation is a kind of scientific activity to investigate and describe the objective things in the natural state system with purpose and plan. Observation is often the premise of experiment, and experiment develops in observation. Experiments are to extract what we want by observing secondary natural phenomena. Angels said: "The experience based on observation alone cannot fully prove the inevitability". The history of science also shows that "proof of certainty" can only be obtained by relying on experimental methods and rational thinking. The main purpose of scientific experiment is to explore the laws of nature under the guidance of scientific theory, and the purpose is to directly transform productive labor into the increase of material wealth. Why? Physical experiments are very important for future study and work.