In order to enhance the safety and efficiency of welding spot grinding in automotive body-in-white production, an automated robotic grinding system integrating active and passive compliance control strategies was developed. Precise sensor calibration was implemented to accurately measure the interfacial forces during robot tool-workpiece interaction, and the force data was fed into an admittance model-based robot controller to achieve constant-force grinding. The results show that compared with traditional manual grinding, the proposed system significantly improves grinding efficiency and ensures operational safety while maintaining grinding quality. It is concluded that the proposed system achieves 1N force fluctuation during grinding, realizing effective constant-force control compared to PD control methods.