This paper introduces the IEC method of square demodulation theory to measure flicker and discusses the digitization and self-check method of flicker meter. Considering the modulation data provided in flicker standard,two different method is used to evaluate the short-term flicker severity Pst and error by combining Simulink with M file programming..Then a short cut method is presented to calculate Gain K so that the measuring error can be revised from 0.00833 to 33.33Hz by using curve-fitting method and the measure accuracy of flicker meter is improved.