The invention discloses vegetable base oil for lubricating oil. The vegetable base oil is prepared from the following raw materials in parts by weight: 20 to 30 parts of soybean vegetable oil, 15 to 25 parts of castor oil, 35 to 45 parts of water, 5 to 9 parts of boracic acid, 8 to 18 parts of oxidized rare earth powder, 4 to 6 parts of viscosity modifier, 1 to 3 parts of defoaming agent, 3 to 5 parts of preservative and 3 to 5 parts of bactericide. According to the vegetable base oil disclosed by the invention, biodegradation can be realized by using the vegetable oil; meanwhile, the vegetable base oil has good lubricating property and stability and facilitates environmental protection.