The calculating method of replacing arc of micro segment tooth shape by Muti object optimum design is proposed. The minimum tooth shape error square of all zero points

the minimum pressure angle error in the pitch circle and root circle is taken as branch objective function. The liner weighted bound method is used to construct united object function. The limited error method is used to determine weighed factors. Finally

three examples are given and calculated by complex shape method. The calculating results show that this method can raise design accuracy.