Abstract: In the paper, Single event upset(SEU) for SRAM is simulated using the software of MEDICI twodimensional device simulator. From the theory, a reliable approach is set up for analyzing device's SEU. Collective charge depending on linear energy transfer(LET) for specific device structure is calculated for different particles LET and the critical charge is provided. The results of simulation are consistent with the model of charging funnel. It has been proven that the models presented in the paper are correct. There are some improvements to be discussed.