In view of the difficult machining characteristics of high volume fraction SiCp/Al composites, this paper researches the grinding force variation of grinding SiCp/Al composites with grinding rod. A diamond grinding rod with a diameter of 3mm is used to grind the SiCp/Al2024 composite with 60% volume fraction by the method of end face grinding. By measuring the tangential grinding forces and normal grinding forces after grinding, the theoretical model of unit grinding force is deduced. According to the experimental parameters of spindle speed, feed rate and grinding depth, this paper derives the theoretical model of grinding force based on SiCp/Al2024 composites. And it clarifies the influence mechanism of grinding depth and feed rate on grinding force and explores the variation of grinding parameters on grinding force under dry grinding condition. Then the variation rule of grinding component force ratio is obtaines. The related research and theoretical model have theoretical guiding significance for exploring the grinding properties of hard-to-machine materials.