Abstract: 55% SiC_p/A356 Al composites were welded by resistance spot welding process,and welding schemes for samples were designed to be directly welded without interlayer and welded with aluminum foil interlayer. The microstructure,shear strength,microhardness,nugget diameter and interface reaction of resistance spot welded joints under different schemes were analyzed and compared. Interface connection model of high volume fraction 55% SiC_p/A356 Al composites was established,and the relationship between joint strength and interface model was discussed. The results showed that under the optimized welding parameters,the joint was well formed without obvious defects,and the SiC particles evenly distributed in the nugget zone without interfacial reactions. After being welded with aluminum foil sandwiched between the samples,strong and sub-weak connection reactions only occurred at the interface. The joint strength increased,and the average tensile shear force was 2 165. 6 N. The average nugget diameter was 9. 5 mm,microhardness of the joint was consistent with its microstructure distribution,and there was no significant difference from microhardness of the base metal.