A series of oil-soluble quadripolymers (denoted as AOSVs) have been synthesized to reduce the viscosity of heavy oil. The quadripolymers were characterized by H-1 NMR spectroscopy, GPC, and TGA to determine the structures and properties. By comparing the apparent viscosities of two different kinds of heavy oil before and after the addition of the quadripolymers, we found that the efficiency of the AOSVs for viscosity reduction was markedly elevated for almost the same molecular weight and mole ratio. Thermogravimetric tests and pumping transportation simulations showed that the AOSVs have good thermal stability up to 320 degrees C and strong shearing resistance. Furthermore, a heavy-component model and a copolymer model were built, and simulations of the interaction process were conducted. The results indicated that the copolymers changed the density of the crude oil by breaking down asphaltene and resin agglomerates to achieve a viscosity reduction.