In this paper, super fine Zn2SnO4 powder was synthesized by mechanochemical method starting from ZnO and SnO2. The structure, size and morphology of Zn2SnO4 were explored with X-ray diffraction (XRD), scanning electron microscopy (SEM) and nitrogen sorption analysis with the Brunauer-Emmett-Teller (BET) method. The result showed that pure spinel Zn2SnO4 powder was prepared after 2h grinding with 3.0KW of power and the particle size was about 200 nm. The degradation experiment of organic dye was performed by the photocatalytic methods on the light of wavelength (= 365nm). The powder can degrade Alizarin red solution close to 90% under U-V light with a 9W high.