The invention discloses a surface modified nano-abrasive silicon slice polishing liquid capable of reducing the roughness of a polished surface and convenient for cleaning. The surface modified nano-abrasive silicon slice polishing liquid is composed of a surface modified nano-abrasive, an ampholytic surfactant, a high molecular surfactant, a nitrogenous carboxylic acid chelator, organic amine and pure water, wherein the pH value is 10.0-12.0; the mass percent of each raw material is as follows: 5-50% of surface modified nano-abrasive, 1-5% of ampholytic surfactant, 1-5% of high molecular surfactant, 0.5-5% of nitrogenous carboxylic acid chelator, 1-10% of organic amine and the balance being pure water; the surface modified nano-abrasive is composite polymer particles formed by modifying the surfaces of organic polymer particles by using SiO2 or Al2O3; and the diameter of the particles is 200-2000 nm.