Taking four different forms of series of planetary transmission system in the series of planetary gear reducer with the same specification（the same output torque）as the research object

the life calculation of planet wheel bearing with the same position

the same bearing capacity is carried out

the results show that the difference is large

and the speed is the larger impact factor.After a thorough analysis of other factors affecting on bearing life

the life correction coefficient is introduced

the poor bearing life is improved

the demand of practical work can be basic meet.