The invention discloses biological lubricating oil for racks. epoxidized soybean oil is used as basic oil, glyceride in vegetable oils is easy to hydrolyze, and biodegradability is high. The biological lubricating oil has good viscosity, lubricating performance and viscosity-temperature performance, as well as high viscosity index and good rheological property; a phosphorus-containing ashless antiwear agent provides improved wear resistance and reduced and stable friction coefficient for the biological lubricating oil; modified graphite has good connectivity with the basic oil, so that chemical stability and thermal stability of the lubricating oil are improved, and the quality of the lubricating oil is improved; modified nano zinc oxide has good dispersity, so that lubricating performance and wear resistance of the lubricating oil are greatly improved; damages of the surface of a rack such as abrasion and scratch can be well prevented, so that the service life of the rack is prolonged; the biological lubricating oil has a scientific and reasonable formula, is environmentally friendly and nontoxic, and is biodegradable.