By using the energy function of forced oscillation， a disturbance source location method based on parameter identification is derived. The method is based on parameter identification of the measurement data obtained through the wide area measurement system（WAMS）. Theoretical analysis shows that the method can be applied to the steady state phase as well as the transient phase of an oscillation. Case studies of actual system oscillations are given to validate the effectiveness of the theory proposed. Both the theoretical and practical case study results show that the method can quickly determine the location of the disturbance source of forced power oscillation， and is easy for online applications.