Many researchers in China have made theoretical and practical research on the effectiveness of small class teaching in mathematics. And these studies have promoted the development of small class teaching in mathematics in a more scientific and efficient direction. This paper sorted out the effectiveness research of mathematics teaching in small class in China since its inception. The author summarized the meaning of the effectiveness of small class teaching in China, the current shortcomings and its improvement measures in various aspects, and put forward the prospect of the effectiveness of small class’s mathematics teaching.