Abstract: This characteristic enables polymorphic circuit can be widely applied to fault diagnosis of digital circuit, synthesis of multifunctional digital circuit, etc.Polymorphic gate plays a vital role in the design of polymorphic circuit.However, until so far, there is no effective method for the synthesis of polymorphic gate.This paper proposes a new method for the synthesis of polymorphic gate, which use graph to represent circuit.The method specially designs a serial of operator to modify the circuit structure or parameter.Experiment results show that the method can synthesis various of polymorphic gate effectively.