There are many factors that affect the quality of products, but some of them play a key role, while others only play a secondary role. How to find out the key factors from many factors? Draw Plato and express these influencing factors with charts, we can find this key factor and then solve it with different management methods. Plato's method is one of the most commonly used tools for quality management. Plato's method, also known as pareto chart or Primary and Secondary Factor Analysis Chart, was first put forward by Italian scholar Dr. Plato when he analyzed the distribution of social wealth in Italy in 1906. In his research, he found that a few people in society have a lot of wealth, while the vast majority are in poverty, that is, he discovered the relationship between "key minority and minor majority". Later, Dr. Zhu Lan, an American quality management expert, applied this principle to quality management. He found that although there are many factors affecting the quality characteristics of products, only a few factors play a major role. This phenomenon completely conforms to the law of "key minority, secondary majority", so Plato's method is used to find the key factors affecting quality.