Helical gear is not entirely a helical gear, it should be said, helical gears are two helical gear meshing manner, by their spatial transmission force in different directions to distinguish. Ordinary spur gears simultaneously into the meshing along the tooth width, resulting in shock and vibration noise, transmission is not smooth. Helical cylindrical gear drive is better than straight teeth, and can be compact for the center distance for high-speed heavy-duty. Helical gear reducer is a novel deceleration gear. It adopts the advanced design concept of optimization and modular combination system. It has the advantages of small volume, light weight, large transmission torque, stable starting and fine transmission ratio. It can be connected arbitrarily according to user requirements and the choice of various installation positions.