The effect of current mismatch on IV performance of photovoltaic (PV) module is analyzed. Based on the current mismatch theory of solar cell and the series and parallel relation of each cell in the photovoltaic module, the influence analysis program of the current mismatch caused by the irradiance non-uniformity and the response difference of the solar cells in the PV module is established. The experimental and theoretical verification of the IV curve and the PV curve of a photovoltaic module under different shielding conditions have been carried out. It is found that the theoretical results are in good agreement with the experimental results. The influence of irradiance non-uniformity on the measurement of optoelectronic parameters of photovoltaic modules under the conditions of different position of reference solar cell is analyzed. Through theoretical calculation, it is found that in order to reduce the influence of the current mismatch of solar cells on the photoelectric performance test of the photovoltaic module, the difference of solar cells in the PV module and the irradiance non-uniformity of the sunlight simulator should both be reduced, and the irradiance intensity at the standard solar cell position should be consistent with the average irradiance intensity of the test area.