The invention discloses an additive composition with excellent water separation performance for no-oil-stain film bearing oil. By using a polyisobutylene amine detergent to substitute polyisobutylene succimide and basic calcium sulfonate, magnesium detergent and dispersant that are used in traditional lubricant additives, the water separation performance (i.e. demulsifying ability) of the no-oil-stain film bearing oil is improved obviously, and the thermo stability, compatibility with base oil, thermal oxide stability, anti-rust property and abrasion resistance are not affected negatively. The adding of the multi-dimensional alcohol ester oiliness agent enhances the abrasion resistance and is helpful for further improving the water separation performance.