The invention relates to a nonionic aqueous POSS-based polymer surfactant which is a polymer obtained by grafting cage polyhedral oligomeric silsesquioxane 3-chloropropyl POSS with methoxy polyethylene glycol or polyethylene glycol and is shown as the following formula. The polymer has good weather resisting property, stability and resistance, can effectively reduce the surface ability of the solution and improve the dispersibility of the cement, and is an excellent nonionic surfactant.