The CSM-CERES-MAIZE model was calibrated and evaluated by using the field and weather data set of a two-year field experiment previously carried out on silage corn at the Agricultural Research Center in Varamin. The data set included soil, crop, and weather data of a two-year corn experiment with four irrigation levels and three N fertilization levels. Twelve treatments were arranged in a strip-plot design in a randomized complete block with three replications during the 2003 and 2004 growing season. Data collected in the field included weight of biomass, leaf area index, and important physiological dates such as silking, anthesis, grain filling, and harvest maturity during the growing period. The maximum leaf area index and weight of biomass at physiological harvest, along with anthesis and maturity dates were used in the calibration process. The biomass weight during the growing season was used for the model evaluation. The results indicated that GENCALC tool is capable enough to be applied for determining genetic coefficients of MAIZE with acceptable accuracy. The result of calibration of the model produced the following statistics, root mean square errors (RMSE) for anthesis and maturity dates were 1 and 2 days, 980 and 1313 kg ha-1 for weight of biomass and 0.75 and 0.44 for maximum LAI in the years of 2003 and 2004, respectively. Genetic coefficient required by the CSM-CERES MAIZE model including P1, P2, P5, G2, G3, and PHINT were found to be 236 (oC), 0.4 (days/hr), 790 (oC), 833, 8.5 (mg/day), and 55 (oC), respectively. The evaluation of the CSM-CERES-MAIZE showed that the model was able to simulate weight of biomass for the silage MAIZE accurately with root mean square errors (RMSE) ranging from 9 to 1483 kg ha-1 and coefficient of determinations (r2) ranging from 0.86 to 0.99 for all of the 12 treatments for two years. It is concluded that the GENCALC tool was capable of successfully determining the cultivar parameters required by the CSM-CERES-MAIZE model and that the model itself was well calibrated for the data set used in this study.