The traditional copying process method of cutting bevel gear produces large error

which leads to allocate load unequally and short the life of gear. However

Variable helix angle bevel gear （VHABG） is a new kind of gear based on numerical control technology. It is a new way to cut large size bevel gear accurately with traditional milling machine. But the volume of the gear is large

cost is high. The above problem limited the application of the gear. A variable helix angle bevel gear is analyzed and its optional mathematics model is established. The optimal solution of the gear is found with genetic algorithms. Compared with the traditional optimal methods

the result shows that applying genetic algorithms to solving the optimization problems with many restraints and many types of variants is feasible

and the method is of importance to the application of the gear.