An ultra-thin deposition of alumina covered the SnO2 photoelectrode surface by atomic layer deposition for dye sensitized cell. Trimethyl aluminum (TMA) and water were used as precursor. The influence of alumina on dye-sensitized cells photoelectric conversion efficiency was discussed. The results showed that atomic layer deposition rate per cycle was about 0.12 nm by use of elliptic polarization apparatus (SE). The SnO2 crystal structure and surface morphology were not changed by deposited alumina as observed by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The dye adsorption capacity increased with the deposition alumina cycles as found by ultraviolet-visible spectra (UV-Vis). Finally, the mechanism of the effect of deposited alumina using atomic layer deposition was discussed.