The invention relates to the technical field of transient state simulation of an electric power system, and discloses an initialization method for a PSCAD self-defined generator controller. The initialization method comprises the following process of 1, establishing an initial value calculation network according to a transfer function of the self-defined controller; 2, extracting an input signal expected by the generator; 3, extracting a variable, used for controller initialization, of the generator, setting a variable and outputting the set variable to be used as a reset signal of the self-defined controller; 4, establishing the calculation network in the PSCAD, enabling the calculation network to output a controller reference signal, and locking the reference signal by adopting a sampling holder at the moment of initialization completion to enable the reference signal to be a constant after the initialization is completed; and 5, establishing the self-defined controller, setting a module comprising a state variable into a reset state, and connecting the reset signal obtained in the step 3, and setting the reset value of the module comprising the state variable into an output value in the corresponding position of the calculation network. By virtue of the initialization method, initialization of the self-defined controller can be realized effectively.