The present invention discloses a preparation method of pure yellow fluorescence water-soluble doped zinc selenide quantum dots, wherein Mn:ZnSe quantum dots are doped with another impurity Ag<+>, such that the intrinsic fluorescence and the defect fluorescence of the ZnSe quantum dots are inhibited while the original intensity of the impurity fluorescence of Mn is maintained so as to prepare the pure Mn yellow fluorescence doped ZnSe quantum dots, and the prepared quantum dots have good water solubility and good fluorescence stability, and only have the one strong Mn fluorescence emission peak. According to the present invention, the one-step synthesis of the pure yellow fluorescence doped ZnSe quantum dots in the aqueous solution is achieved, and the preparation method has advantages of simple operation, good repeatability, green environmental protection, low cost and the like, and can be used for mass production of the quantum dots.