Based on mechanics of anisotropic material and Maxwell's electromagnetic theory, the piezoelectric effect of piezoelectric material (SiO2) under multidimens ional forces has been studied. Exploring the distributions of stress field and polarization electric field inside the circular wafer, the piezoelectric equations between forces and induced charge on wafer's surface are established. Then the simulation analysis is performed by the FEM, obtaining polarization electric field and electric potential in the wafer. Results of both analyses show that f dividing the wafer's surface into four areas, the quantity of electric charge on each area is linearly related to bending moments and normal force, which gives a new way to measure multidimensional forces by a single quartz wafer. The study also provides the theoretical feasibility for developing a novel small-size multidimensional forces sensor.