When Colossal Magnetoresistance films are grown on lattice mismatched substrates, the strain on the film/substrate interface induces a strong strain that altered the intrinsic properties on transport and magnetic measurements. The transition temperatures of La0.7Ca0.3MnO3(LCMO) and La0.7Sa0.3MnO3(LSMO) thin films are lowered by both tensile and compress strains, while La0.8Ba0.2MnO3(LBMO) films may be increased or decreased dependent on the type of strains. When La0.8Ba0.2MnO3(LBMO) films were grown on SrTiO3 (STO) substrate by a standard off-axis RF sputtering technique, the compressed strain enhanced the transition temperatures. When La0.8Ba0.2MnO3(LBMO) films were further annealed at higher temperature, the transition temperature was increased up to temperature that was never been achieved, and this phenomena can not be explained solely by the strain effect. In this study, Secondary ion mass spectroscopy and X-ray reciprocal mapping were used to investigate the possible cause of the extra enhancement in transition temperatures. It is found that under a fixed annealing condition the substrate element, Sr, diffuses partially into the film that separated the films into the top layer and the bottom layer acting as La1-x(SryBa1-y)xMnO3 with higher transition temperature. The TC enhancement can be attributed to the combination of the strain and interdiffusion effects.