If students master what they have learned through infiltration, they tend to cultivate mathematical computing ability in the cultivation of mathematical ability; The content of junior high school mathematics is abstract and complicated. First, some knowledge in junior high school is based on what you have learned in primary school. Secondly, junior high school focuses on cultivating students to gradually transition from intuitive perception to logical argumentation. Secondly, for the connection between primary school and junior high school, we should pay attention to the following points: 1. In algebra, the knowledge of algebra in junior middle school has been expanded and improved compared with that in primary school. In primary school, only contact with non-negative content. After junior high school, the concepts of real number, reciprocal and absolute value were gradually introduced, and then algebra and algebra addition and subtraction, as well as equations, inequalities and functions were involved. Secondly, geometrically, the plane and three-dimensional figures such as rectangle, triangle, cylinder and cone learned in primary school will become known conditions for calculating other problems after junior high school. Attention should be paid to establishing the concept of space and developing geometric intuition. For Liu Yujia's mathematical connection, I think we should start with the following points: First, the knowledge of the seventh grade last semester should be systematically taught. Starting with the concept of rational numbers in the first chapter, this paper systematically studies the concepts and points of positive numbers and negative numbers, the positional relationship of rational numbers on the number axis, the characteristics of antonyms and absolute values, addition, subtraction, multiplication and division of rational numbers, and multiplication of rational numbers. Secondly, in view of Liu Yujia's personal situation, I think we should strengthen the improvement of practical problems, especially the training of linear equations, and pay attention to the transition from the thinking of solving mathematical problems in primary schools to the thinking of solving equations in junior high schools. Thirdly, if time permits, it can involve the knowledge of geometry, mainly the knowledge of geometric figures, the relationship between points, lines and surfaces, and the knowledge of angles.