The invention provides a preparation method of an in-situ synthesis oxide dispersion strengthening CoCrW alloy. The preparation method comprises the following steps that CoCrW alloy powder is subjected to laser melting treatment in an inert gas atmosphere to obtain the in-situ synthesis oxide dispersion strengthening CoCrW alloy, wherein the oxygen content in the gas atmosphere is 200 ppm to 2, 000ppm, the CoCrW alloy powder contains Si element, and the weight content of the Si element in the CoCrW alloy powder ranges from 0.1% to 2%. According to the preparation method, because a spherical / nearly spherical nanometer oxide dispersion precipitation phase is synthesized in situ in the CoCrW alloy through a selective laser melting technology, and the phase is in an amorphous state, no latticematching problem exists between the phase and an interface of a CoCrW alloy matrix, and an interface transition layer is tightly combined. According to the in-situ synthesis oxide dispersion strengthening CoCrW alloy, a large number of oxide dispersion precipitation phases are uniformly distributed inside, the bonding capacity of the CoCrW alloy and ceramic is remarkably improved due to existenceof the oxide dispersion precipitation phases, the phenomena of cracks and ceramic collapse are avoided, and the service life of porcelain teeth is prolonged.