Based on the EHL theory and considering the variational factors,such as equivalent curvature radii,entrainment velocity and load,the pressure and film thickness along the meshing tooth profile of the cycloid pinwheel planetary gearing mechanism were calculated by using the multigrid method,and the difference between transient and steady-state of this mechanism is discussed.The results show that the variational factors have evident influence on the film thickness,but less influence on the pressure.Compared with steady-state,the values of central and minimum film thickness are lower during the first half of meshing and higher during the latter part of meshing at transient state.During the meshing in transient state,the value of central film thickness is firstly declined rapidly and then remains unchanged,finally starts going up,the value of minimum film thickness is firstly declined rapidly and rises immediately.During the meshing in steady-state,the minimum value of above-mentioned film thickness appears in the earlier stage and the end of meshing.