The invention discloses a compound multifunctional asphalt pavement sealant and a preparation process thereof. The main components of the sealant include: 100 parts of mixed modifier-modified asphaltwith 35 percent of 40-mesh rubber powder, 45 percent of 60-mesh rubber powder and 20 percent of 80-mesh rubber powder; 15 to 30 parts of functional component agent A; 10 to 35 parts of functional component agent B; and 5 to 25 parts of functional component agent C. The main components of the functional component agent A are coumarone-indene resin, trimethylolpropane, fine talcum powder, p-aminobenzoic acid and the like. The main components of the functional component agent B are diphenylmethane diisocyanate, butyl epoxy stearate, bisphenol-A epoxy compatibilizer, trimethylolethane and the like. The main components of the functional component agent C are microcapsules, vinyl glass flake mortar, polyvinyl alcohol-modified high-sodium bentonite particles and the like. According to the invention, after the functional component agents A, B and C are prepared, proportion is designed to carry out compounding, and the compounded sealant not only can fill cracks, but also can seal the cracks. The invention is applicable to different types of cracks, and according to causes of crack formation, different amounts of functional component agents A, B and C can be added. The sealant compounded bythe invention has high bonding strength, good sealing property and waterproofness and excellent high-temperature stability and low-temperature bonding property, having high application and popularization values.