The invention provides a preparation method for a cemented carbide product. According to the preparation method, ultrafine mixed powder with specific components is adopted; a trace amount of metal Mo element is added to increase wettability and heat conductivity of the alloy; a trace amount of Y(NO)3 is added to play a purifying effect; and a trace amount of VC and Cr3C2 is added as a grain growth inhibitor to inhibit the growth of grains. On the premise of meeting the proportion relationships limited by the invention, the mixed powder is successively subjected to process steps of compression molding, isostatic cool pressing, atmosphere dewaxing, vacuum sintering and hot isostatic pressing, thereby effectively eliminating residual pores in the cemented carbide product, improving texture structure of the material and increasing properties of the material. The strength, hardness and service life of a finally produced cemented carbide product, particularly a large size cemented carbide holding-up hammer, are greatly increased.