Abstract: A new kind of helical gear with asymmetric involute teeth was proposed in order to improve the transmission performance and bearing capacity.A rack cutter was designed for manufacturing the gear.The parameter relationship between the rack cutter and the gear was analyzed.Tooth profile equations of the gear's transverse section,normal section and axial section were discussed and a helicoids equation along the axial was derived.The meshing theory of the gear pair was studied,and the internal and external meshing coordinate transition matrices of conjugate tooth profiles for the gear were deduced.Based on the parameter relationship of the gear,three-dimensional software was used to build a parameterized three-dimensional model of the gear,which verified the correctness of the mathematical model and theoretical analysis.