Based on measuring the intensity of components of polarized light, the methods for determining the parameters of a wave plate are discussed and uncertainty of measuring arbitrary wave plate is indicated by the methods. It is concluded that the real phase retardation and fast axis of a wave plate cannot be determined by this kind of methods, because the phase retardation of a wave plate is a multiple valued function of measured light intensity. A method for measuring phase retardation and fast axis of a wave plate using Michelson interferometer is brought forward, in which the rainbow fringe of the Michelson interferometer could be used as an indicator for the zero optical path difference. The method was demonstrated by measuring a commercial quarter-wave plate. The influence of the dispersion of the wave plate material on the measurement is analyzed, and the applicable scope of the method is discussed.