Liu Hui focuses on the relationship between the formulas and solutions of nine chapters of arithmetic, as well as various parts of mathematics. Take the volume problem as an example. Chapter 9 Arithmetic is mainly based on verification, and its correctness is the result of induction. Liu Hui pointed out: "No turtle nest, no yang horse, no yang horse, no cone pavilion, etc. are the masters of merit." The volume of any tetrahedron is close to 16abh. He divided polyhedron such as square cone, square pavilion, vegetation, vegetation and envy wood into cuboids, cubes, horses and turtles to prove their volume formulas. Liu Hui's polyhedron theory is a theoretical system based on cuboid, with the proof of tetrahedral volume formula as the core and deductive reasoning as the main body. Liu Hui's other theories can be similarly analyzed. In a word, mathematics has formed a unique system in Liu Hui's mind. Starting from the unification of rules and measurement, the definitions of area, volume, rate and positive and negative numbers are derived, and the methods of homogeneous principle, complementary access principle and infinitesimal division are used, with deductive logic as the main reasoning method, calculation as the center and rate as the subject. It is a "promise without promise" without circular reasoning, which fully embodies the mathematical knowledge of China people until the 3rd century. Liu Hui's Notes on Nine Chapters Arithmetic contains not only concepts and propositions, but also logical reasoning linking these concepts and propositions. Its appearance indicates that ancient mathematics in China has formed its own theoretical system.