Based on the type of DZLY180 gear reducer,aiming at the particularity of the tooth profile of point- line meshing gear,the curve equation of the tooth profile of point- line meshing gear is applied to calculate some coordinates on the tooth profile curve after modification. The cubic spline curves are used to fit the data,and 3D Software Solidworks is used to fit the tooth profile curve of point- line meshing gear. Then the three- dimensional modeling is carried out,the interference- free assembly of the gear is completed. The simulation results show that,the overall interference- free assembly in the meshing process of the point- line meshing gear is realized by the method.