Causal analysis is a method of forecasting by using the causal relationship of things' development and change. It is based on the causal relationship of the development and change of things, grasps the relationship between the main contradiction and the secondary contradiction of the development of things, and establishes a mathematical model to make predictions. Predict the market by causal analysis, mainly by regression analysis. In addition, the calculation of economic model and input-output analysis are also commonly used. Only regression analysis is introduced here. Regression analysis is a mathematical method to study the relationship between two or more variables. If only two variables are involved, it is called unary regression analysis or unary regression analysis; If more than two variables are involved, it is called multiple regression analysis or multiple regression analysis. Know the reason, measure the result or check the reason according to the causal relationship between things. Causality prediction analysis is the basis of the whole prediction analysis. Causal analysis (technology) is applied to project management, which is a method to study and discuss the existing problems of the project step by step with the results as the characteristics and the reasons as the factors. The deliverable result of causality analysis is causality diagram. Once the causal analysis diagram is determined, the project team should explain it, and confirm the most basic reason through statistical analysis, testing, collecting more data about the problem or communicating with customers. After confirming the basic reason, the project team can see that the characteristics of the problem are always affected by some factors. We find out these factors through brainstorming, and organize them together with the eigenvalues into a well-defined and well-organized graph, and mark the important factors, which is called the characteristic factor graph. Because of its shape like fishbone, it is also called fishbone diagram (hereinafter referred to as fishbone diagram), which is an analytical method to see the essence through phenomena. At the same time, fishbone diagram is also used to visually represent the process of production workshop in production.