When designing certain artillery’s planetary transmission of fluid gearbox, it is hard to calculate by general design method, because the plant frame is abnormity three-dimensional entity, and the plants distortion affects the contact stress of joggled gear tooth. In this paper, by the APDL language programmer, the three-dimensional entity of certain artillery’s planetary transmission is established; the finite three-dimensional contact is analyzed by ANSYS; the plants distortion affects is discussed by the choice of the constant FTOLN and FKN, the influence is analyzed that the plant frame’s distortion to the stress of joggled gear wheels, as a result, the planet frame’s transmutation quantity is direct proportion with the gear wheel’s most joggled stress by ANSYS.