Double helical synchronous belt transmission receives much concern with its excellent characteristics of de-noising

low transmission error and high carrying capacity.The profiles of synchronous belt and belt pulley were studied based on conjugate-curvature high degree contact mesh theory in the text.And the main profile parameters of transmission belt and belt pulley with two steps infinitesimal neighborhood gap were proposed.Finally the 3D profiles model was built.It laid a solid foundation for the manufacturing and transmission performance research for double helical synchronous belt transmission.