The special fixtures used for trimming automobile dashboard by robot are expensive, unadaptable, and not easy in maintenance. In view of these problems, an entirely new clamping scheme based on the idea of multipoint support is proposed. The automobile dashboard and fixture model were established and simulated assembly by threedimesional (3D) modeling software SolidWorks. The deformation of the being milled workpiece was analysed by numerical analysis software ANSYS workbench in the scheme. Aimed at the result of numerical analysis display, an improved clamping scheme was put forward. In accordance with the improved scheme, reset the boundary conditions, numerical analysis was made again. The results show that the improved multipoint support scheme can meet the accuracy requirements of trimming.