Abstract:New transformer protection principles based on models calls for accurately identifying transformer winding parameters.Parameter identification equations of single-phase double-winding transformer and three-phase three-winding transformer ale deduced.And then a new parameter identification algorithm is put forward on the basis of particle swarm optimization algorithm.The new algorithm eliminates the limitation of least squares method and can realize precise identification of parameters of transformer winding.The simulation of Matlab/Simulink shows that the algorithm can correctly identify leakage inductance and winding resistance parameters of transformer.This algorithm has a good application prospect.