The present invention discloses novel polymorphs I, II, and V of a [2-(4-(3-trifluoromethyl-benzyl)piperazin-1-yl)ethyl]-2,3-dihydro-1H-benzimidazol-2-one and a preparation method and application thereof. The polymorph I is a trihydrate crystal, the polymorph II is an anhydrous crystal, and the polymorph V is an anhydrous crystal. When compared with an existing crystal form, the novel polymorphs provides significant advantages in terms of solubility and preparation techniques.