Abstract: The primary purpose of regional simulation is to predict the crop yield spatially and temporally,with available data set.Performance of regional simulation and its uncertainties were analyzed,in the case of CERES-Maize model.The results show that the average relative root mean square error(RMSE) between simulated and census yield across the whole of China is 29.9%,with an agreement index of 0.78.Of all the 2144 simulation grids,71.3% grids show RMSE less than 30%,and 29.4% of which with RMSE less than 15%.The performance is different among regions.The best performance occurs in AEZ 2,the largest maize cultivation areas taken 34% of maize cultivation area of China,where 63.2% grids have RMSE less than 15%.Considerable uncertainties exist in the regional simulation,including limitations of crop model,the aggregation of coefficient parameters and management practices to AEZ system,the rationality of definition of Agro-Ecological Zone system to present climate,and errors in dataset,etc.

Key words: CERES-Maize, Regional application, Uncertainties