The invention discloses an oil composition for emulsified diesel oil engines. According to the oil composition, II-class base oil and polyinternalolefins are used as base oil, and a plurality of additives are matched. The oil composition comprises an antirusting agent, an oxidation-corrosion inhibitor, an anti-foaming agent, a viscosity index improver, a metal deactivator, a clearing agent, a dispersing agent, an antioxidant, a reinforcing agent, an oiliness agent and an anti-creaming agent. The oil composition for the engines has excellent clean dispersion effect, so that sediments of piston rings are reduced; the oil composition has excellent viscosity-temperature characteristics, alkali value retentivity and acid neutralization capacity, and can inhibit the generation of black oil sludge, so that the engines are relatively clean; the oil composition has good high temperature oxidation resistance stability, high shear stability, anti-emulsifying property, rubber compatibility, good low temperature startability, excellent fuel economy performance and has no corrosion and rusting for moving parts, enough oil film strength of oil is guaranteed, and the abrasion and the oil consumption are reduced.