In order to solve the problems of optical signal detection by photocell in laser simulation countermeasure,the paper suggests the methods to remove the strong background light and miscellaneous interferences by improving circuit parameters and designing a anti-saturation photoelectric circuit.Computation formulas of photocell internal noise were given.A narrow pass-band filter was designed.Coded laser signal with a frequency of 27.934 kHz was successfully detected under the interference of strong background light.