A new kind of photovoltaic array simulator utilizing TMS320F2812 DSP as the controller and Buck circuit as the main circuit was put forward. The simulation algorithm controls the duty cycle of the electronic power switch in buck circuit by utilizing the difference of actual load current of the simulator and the characteristic current of photovoltaic array, and then adjusts the output voltage of the simulator so as to make the operating point of the simulator approximate the working point of photovoltaic array on the I-V characteristic curve. In DSP, the mathematical model of the I-V characteristic curve for the kind of photovoltaic cell array was stored. The characteristic current can be calculated by means of the model corresponding to different quantity of illumination (S) and ambient temperature (T). A lot of simulating and experiment results have shown that the simulator can simulate perfectly the I-V characteristic curves of photovoltaic array with outstanding performances. Its approximate and stable time is about a quarter of the time for traditional point by point approximate. The approximate error is lower by 4% and the overshoot is lower by 1%.