In view of the interference of assembly stress from installation of a bar-shaped balance on component output values, the reason is thought as inadequate length of clamped end of the component. In this paper, with the prerequisite of no change on length of centre part, through changing length and diameter of the clamped end of the balance component, ABAQUS was used for finite element simulation and analysis. The result shows length of clamped end of component effects more on the measured values, but the effect of diameter is not obvious. The conclusion of this paper can provide a reference for balance design and use.