A disclosed preparation method for high-performance WC-Co nanocrystal cemented carbide comprises: taking nanometer tungsten carbide (WC) powder, ultrafine cobalt (Co) powder and ultrafine vanadium carbide (Cr2C3) powder as raw material powders, employing an alcohol wet grinding technology, and performing vacuum sintering and hot isostatic pressing sintering to prepare the WC-Co nanocrystal cemented carbide. By employing the above method for preparing nanocrystal cemented carbide, WC crystal grain structure is complete and clearly visible, by employing a method prescribed in ISO4499-2 for calculating two hundred or more WC crystal grains and averaging, the WC average crystal grain is less than 150 nm, the hardness HV30 is 1900 or more, the strength TRS is 4000 MPa or more and the metallographic structure is A02B00C00. The technology is simple, the process control is convenient, the production cost is low, and the prepared nanocrystal cemented carbide has the advantages of high densification degree and excellent performances.