Abstract: Monte Carlo method model was improved from the aspects of grain oriention number choice and grain growth probability. According to grain growth mechnism, the model was applied to simulate the nano Al2O3 ceramics grain growth process at different sintering temperatures and times. The simulated results were compared with the actual experiment results. The results show that using the modified model, the simulation efficiency of the grain growth process simulation could be improved availably. The sintering test results were consistent with the simulation results, and the modified model could accurate and fast predict the ceramics grain size.