In order to further improve the stability analysis of a power system， a model for the turbine governing system is developed with the realistic governor model and the prime mover model is expressed as a higher order nonlinear transfer function. Three kinds of prime mover model identifying methods are built， namely， the improved least squares（LS） algorithm， genetic algorithm（GA） and particle swarm optimization（PSO） algorithm. Compared with the measured dynamic process， the simulation results of the custom model is more realistic than the model provided by BPA4.0 and capable of meeting the demand for power system stability analysis.