Sn₁₅Sb₈₅ thin films with different thickness are prepared by magnetron sputtering. The evolution of Sn₁₅Sb₈₅ thin film from the amorphous state to the crystalline state is studied by an in-situ resistance temperature measurement system. The crystallization temperature, electrical resistance, crystallization activation energy, and data retention capacity of Sn₁₅Sb₈₅ thin film increase significantly with film thickness decreasing. The near infrared spectrophotometer is used to record the diffuse reflectance spectra of amorphous Sn₁₅Sb₈₅ film. The results show that the band gap energy increases with film thickness decreasing. The surface morphology of Sn₁₅Sb₈₅ film after being crystalized is observed by atomic force microscope, which shows that the thinner film has lower roughness. The analysis of X-ray diffraction indicates that the grain size becomes smaller and the crystallization may be inhibited by reducing the film thickness. T-type phase change memory cells based on Sn₁₅Sb₈₅ thin films with different thickness are fabricated by the CMOS technology. The electrical performances of phase change memory show that the thinner Sn₁₅Sb₈₅ film has a larger threshold switching voltage and smaller RESET operation voltage, which means the better thermal stability and lower power consumption. The outcomes of this work provide the guidance for designing the high-density phase change memory by reducing the size of Sn₁₅Sb₈₅ thin film.