Abstract: Modern manufacturing and automatic production have higher and higher requirements for the power and motion of the transmission system. Non-circular gear can realize non-uniform gear ratio. It has advantages of compact structure, accuracy gear ratio and good dynamic performance than that of the connecting rod and has low cost than that of the servo motor system. Until now, a great deal of research on the gear mechanism, gear design and gear manufacture have been conducted by domestic and foreign scholars. A comprehensive analysis of the existing researches was made and the direction of non-circular gear transmission technology was pointed out in this paper.