Planetary gear transmission is an important form of transmitting motion in the field of machinery. The problem of transmission design and the load sharing of planetary gear trains are two important aspects in the study of planetary transmission system. In this paper, the research status of planetary gear transmission was sum- marized from four aspects, including design theory, analysis method, load sharing characteristics and experimen- tal study. From the existing research results, domestic and foreign scholars mainly analyze and study the trans- mission scheme of planetary gear trains which have been designed, and it is urgent to develop the optimization scheme of planetary gear transmission based on active design. The current manufacturing has reached a relatively high level, simply using existing methods to suppress the planetary row eccentric load, has been difficult to sig- nificantly improve the performance of planetary gear transmission, it is urgent to explore new methods to sup- press planetary row eccentric load. Therefore, on the basis of absorbing and digesting the existing research and development technology of planetary gear transmission, it is necessary to improve and innovate the eccentric load suppression method of planetary row and the design theory of multi -stage gear transmission system, so as to adapt to the development trend of transmission equipment toward large models, reduce the failure rate of large gearboxes, and increase their service life.