A new type of axial pin small tooth difference planetary gear drive mechanism which can realize power transmission between parallel shafts is introduced in this paper.Planar multicrank mechanism is used as input unit of the tooth difference planetary gear drive and the offset crank mechanism is replaced by axial bin mechanism. Its structure,working principle to overcome dead point and geometric conditions of movement are analysed.In accordance with the formal constraints in planar multicrank mechanism,force analysis model is set up on the basis of contact deformation coordination of kinematic pairs.Systematic force analysis including bearing load and contact state of the pins has been made by method given in the paper.