This paper, raises two methods of distinguishing the seismic phase. By the greatest eigenvalue method, the arrival time of fast and. slow shear-wave and convert P wave may be determined. By the method of wave distinguishing factor,fast shear-wave arrival time and wave sequence may be determined. Combining these two methods, the possbility of taking the conversion P wave as fast shear-wave may be removed. By using the above-mentioned methods to 1983 Luquan Ms 6.1 earthquake, the results show that the fast shear-wave polarization direction is in keeping with what EDA hypothesis raised.