Aiming at the problem of particle agglomeration in traditional powder hot pressing fine-grained diamond grinding tools, which is easy to produce deep scratches on the surface of grinding SiC ceramics, a sol-gel forming fine-grained diamond abrasive tool for precision grinding of SiC ceramics is proposed, and grinding process is studied. Diamonds and fillers are sheared and dispersed to prepare polyvinyl alcohol-phenolic resin composite gel glue in the gel glue, and the obtained slurry is poured into a mold, repeatedly frozen at a low temperature of –20 ℃ to gel, then dried and sintered to obtain 2.5 μm diamond sol-gel abrasive tools. Grinding SiC plane mirror with the prepared diamond sol-gel grinding tool, the surface grinding quality under different grinding speed, feed speed and grinding depth was compared. The molecular chain of polyvinyl alcohol phenol-formaldehyde resin has formed physical gel at a low temperature. The strength of the gel binder with uniform distribution is high. The strength of the gel grinder is higher than that of the hot pressing abrasive tool. This method can solve the problem of phase agglomeration and microstructure inconsistency in the traditional powder compaction process. The grinding results show that when the grinding feed speed is 0.008 mm/min, the grinding speed of the tool is 1450 r/min, the grinding depth is 0.016 mm, and the rotation speed of the rotary table is 60 r/min, the surface roughness is lower than Ra 3.5 nm, and the surface quality is better than that of the hot press grinding tool. The Flatness PV values of three areas with a diameter of 100 mm are all less than 0.5 μm. Fine-grained diamond grinding tools are successfully prepared by using polyvinyl alcohol phenolic resin composite gel. By optimizing the grinding parameters, new processing technology is provided for the surface processing of the SiC flat mirrors.