Abstract: Timely and accurate assessment of the impacts of drought on maize in the maize producing areas in Southwest China for regional agricultural production planning has become increasingly important with more frequent and severe drought events. In order to effectively study the impact of drought on crop production, the assessment method of agricultural meteorological disaster should be expanded. This study evaluated the application of WOFOST model using field experimental data of maize and the parallel daily meteorological data collected at eight typical stations in Southwest China. The WOFOST model was improved for the phenology and photosynthesis modules before application. Based on the improved crop model, the historical impacts of drought on maize production in terms of change trend in maize yield for typical drought years were analyzed. The results showed that the normalized root mean squared errors (NRMSE) between the simulated and observed maize phenology reduced from the range of 3.25%-6.95% to 1.48%-3.07%, R² increased from 0.57-0.79 to 0.63-0.99 and the average simulation precision increased from 74.12% to 78.9%. NRMSE between simulated and observed maize yields reduced from the ranges of 7.88%-11.99% to 3.07%-6.79%, R² increased from 0.52-0.93 to 0.77-0.98 and the average simulation precision increased from 75.7% to 80.95%. The average simulation precisions of maize yield were 69.8%, 75.9% and 78.1% in typical drought years of 1987, 1992 and 2006, respectively. The above results showed that the simulation precision of the phenology and yield of maize improved significantly and the model was therefore fully applicable in simulating the impacts of drought on maize production. The study provided a scientific technique for the drought assessment on regional maize production in Southwest China.