Existing fitting algorithms for photovoltaic (PV) module correction IV curve under standard condition suffer from several problems, such as overcomplicated calculation and lack of accuracy. To improve fitting accuracy under condition deviated from STC, a fitting algorithm based on solar cell fourparameter model was proposed. The module’s IV mathematical model for curves fitting is calculated by the algorithm through selecting six points as fitting points near the maximum power point. A selfadaption fitting point selection method also was presented for accuracy improvement because different PV modules have different optimal interval among fitting points. Moreover, a type of IV tracer employing capacitors array as load to increase number of data points near the MPP was developed to improve fitting point’s accuracy. Several MATLAB simulations and actual measurement were carried out, which show that the proposed algorithm fitting results were superior to that of polynomial fitting algorithm. And the designed IV tracer not only has excellent performance but is suitable for engineering surveying.