Abstract: The basic method of uncertainty evaluation is GUM uncertainty framework(GUM) at present. On some conditions, GUM can be applied correctly. But when the model is complicated, all the applying condition can’t be ensured to meet. Compared to GUM, the validity range of MCM is larger, we can use MCM to validate GUM uncertainty evaluation with appropriate software. It’s suggested that the results can be compared which are obtained by GUM and MCM. If the results are satisfied, the GUM is applied correctly. Otherwise, MCM or other replacement must be considered. Concerning the example of mass calibration, the two methods are introduced to validate GUM uncertainty evaluation using MCM.