A system-wide identification methodology for multi-generators in power systems is proposed， i.e. to identify the parameters of multi-generators simultaneously with the rotor angle data from wide area measurement system（WAMS）. The parameter identifiability of different Park models is analyzed by using the trajectory sensitivity method， and the results indicate that most of the parameters are identifiable but some of the parameters are not identifiable. The strategy is developed for the simultaneously identification of multi-generators， i.e. classification of generators， identification of parameters under both steady and dynamic states， identification of the key parameters and emphasis on system wide characteristics. An ant colony optimal algorithm based method is proposed for the parameter identification， and the procedure for implementation is given. The simulation example validates the feasibility of simultaneously identifying the parameters of multi-generators.