The change in resistivity caused by the mechanical deformation in a micro-accelerometer was used to design an accelerator to measure physical quantities such as high g acceleration. The process and a solid model were constructed in CoventorWare. With changing the position of a piezoresistive sensing element on the fix-end cantilever,the optimizing location of the sensing element as well as the relationship between the output current and the location are obtained by using Finite Element Mothod(FEM) in the MemPZR module. Changing the sensitivity by the same percentage, it is proved that electric conductivity changes are coincident with the sensitivity changes of the element. When 20 kg acceleration is inputted, the potential distribution of piezoresistor device terminals,the corresponding stresses of the piezoresistive element and the current location are also obtained,which testifies the anti-over loading ability from the stress location in the fix-end cantilever.