Twin-rotor piston engine is exceedingly compact, and several times more power dense than conventional IC engines. It is necessary to analyze the transmission characteristics of the special geared linkage mechanism which is used for the power transmission equipment of the engine. Transmission angle is mainly adopted in order to obtain the transmission characteristics. Firstly, the force transmission behavior of one end of the output component is derived through the force analysis of the planet gear. Secondly, the torque transmission angle is proposed based on the multi-point force situation. Lastly, the torque transmission angle is depicted and analyzed in detail through the equivalent composite force graphical method. The result shows that the geared linkage mechanism will not produce counteractive torque to the rotation direction and has no dead point.