Based on features and the principles of department of planetary gear kinematic,this thesis proposes a signal flow graph method to calculate the characteristic parameters of the complex planetary gear transmission system. To introduce the concept of signal flow graph to the single degree of freedom in the parameter calculation of planetary gear system,and adopt the solution to establish the ’XP’system,’PX’system,T-type compound system,∏-type compound systems and E-type mixed signal flow graph model of the system. Reuse the calculation rules of signal flow graph,and got a variety of planetary gear train speed relation of input and output of the transmission components,the conversion ratio of the transmission system. The method was intuitive,This way can do visual analysis of planetary gear transmission,and can deal with the characteristics of power flow analysis,A new technique for the complex planetary gear kinematic system characteristic parameter calculation of the research was provided.