The invention provides a method for preparing water-phase non-toxic quantum dot zinc telluride. The preparation method comprises the following steps: a, NaHTe preparation: sodium borohydride is dissolved in deionized water, tellurium powder is quickly added into the solution, and a reactor is sealed by a rubber plug which is provided with a pin hole to be communicated with the outside for releasing hydrogen generated in reaction; in the reacting process, the system is cooled by ice-water bath, after several hours, the black tellurium powder disappears, white sodium borate is generated, and upper clear NaHTe solution is light purple; b, preparation of Zn+TGA thioglycolic acid precursor: Zn(NO3)2 is added to a conical flask, a certain amount of TGA is added to the solution by a miniature pipetting gun, pH of the mixed solution of the Zn(NO3)2 and the TGA is adjusted by NaOH after sufficient stirring, the solution is kept for later use after sufficient stirring; and c, preparation of water phase ZnTe quantum dot: the mixed solution prepared in the step b is deoxidized by N2 gas, and the NaHTe in the step 1 is quantitatively taken by a particle injection needle, and is injected into the mixed solution, and the solution is continuously stirred to obtain ZnTe nanometer crystal.