Taking a helical gear pair as the research object，the analytic algorithm of time-varying mesh stiffness of helical gears with temperature was proposed based on slicing method and integral thought. In this algorithm，the tooth profile deformation caused by change of tooth contact temperature，elastic deformation of tooth contact，bending，shear，axial compression and the wheel were taken into account. The accuracy of the algorithm was verified by using finite element method. Then the influence of working parameters，such as friction coefficient，input torque and input speed，on the mesh stiffness of gears was analyzed. The results show that the mesh stiffness of teeth increases in the whole meshing process after considering the influence of temperature. Besides，the body temperature and instantaneous flash temperature of helical gears increase with the increase of friction coefficient，input torque and input speed，so the single mesh stiffness and the mean of total mesh stiffness increase. The research results can provide a theoretical basis for accurate and efficient dynamic analysis of the high-speed and heavy-duty gear system.