The sol-gel method is a method of dissolving a silicon source in a solvent, then performing hydrolysis and polycondensation to form a sol, and then obtaining a gel by drying and heat treatment. When preparing cationic silica sol, cations can be introduced during the sol formation process to neutralize the negative charge on the surface of the silica sol particles to form a positively charged silica sol. The advantage of the sol-gel method is that the composition and structure of the silica sol can be precisely controlled, and it is suitable for preparing high-performance cationic silica sols.