This paper focuses on the inability to obtain the phase-frequency characteristics when testing the frequency response of photoelectric detecting elements by using the step response method.It sets up an equivalent circuit model that provides the same parameters as the actual devices by using the Multisim software and proposes a method for the simultaneous frequency response measurement of the amplitude-frequency and phase-frequency characteristics on the basis of the relationship between the phase difference and the time difference of the phase-frequency characteristics.The measurement results of amplitude-frequency characteristics are consistent with those by using the traditional step response method.The phase-frequency characteristics of photoelectric diodes have major influences on the design of high-speed receiving systems.