Abstract:A computer simulated sampling processes is proposed in this paper. With repeat tested of different sample masses, and calculated the standard deviations of these results obtained from these tests, a fitting curve of sample masses to standard deviations was formed. Base on the uncertainty of characteristic value, and fitting equation, the minimum sample mass was determined. Because the sample was took one grain by one grain, without any other test steps, the error was came from the heterogeneity of sample only, so the minimum sample mass determined was reliable. Moreover, computers operate more quickly and are convenient to alternate parameters, these made simulations are closer to reality of samples.