The invention provides a preparation method of metal powder. The preparation method of the metal powder comprises the following steps that (1) after being hydrogenated and crushed, metal raw materials are graded, so that metal particles are obtained; (2) the metal particles are dehydrogenated, and then dehydrogenated metal particles are obtained; (3) ball-milling treatment is conducted on the dehydrogenated metal particles, and then metal powder bodies are obtained; and (4) the metal powder bodies are deoxidized, so that metal powder is obtained. Compared with the prior art, the metal powder is obtained through the hydrogenating and crushing method, especially the ball-milling method is adopted for preparation of the metal powder after dehydrogenating treatment, the metal powder prepared in this way is narrow in size distribution, edges and corners of the particles are smooth, the metal powder prepared in this way has good spreadability and flow ability, when the metal powder is used as 3D printing raw materials, the product manufactured can be protected against the hollow defect and the bubble defect, and the quality of the product is improved.