A reactive co-deposition processing for obtaining high-quality single-phase Bi2Sr2Cax-1CuxOy(Bi2212) thin films has been investigated using molecular beam epitaxy (MBE) with 2.7 x10-3Pa ozone gas introduction for oxidation. The thin films with a constant composition of almost 2:2:1:2 were designed to be fabricated at the substrate temperature between 675 and 780℃, the substrate temperature dependence of the surface morphology and the emergence phases were investigated in detail. A noticeable result is that the distribution of Cu element in the thin films is sensitively changed with the substrate temperature. At 750℃ it is inclined to locate in the periphery of each grain through the diffusion process. At 780℃ the Cu-compositional fluctuation brought around the dendritic crystal growth in the thin films. Below 705℃, the Bi2212 single-phase cannot be achieved in the thin films.