By combining experiments and first-principles calculations, Y-doped Sb7Se3 thin films were successfully fabricated and investigated. Our results suggest that Y is one promising dopant for simultaneously enhancing thermal stability, increasing phase change speed and reducing power of consumption. In particular, the temperature of ten year data retention for Y-doped Sb7Se3 thin film increases to 118.5 degrees C. The fast phase change speed (10 ns) can be realized for Y-doped Sb7Se3 thin film, which is fairly competitive with that of traditional GST (100 ns). Theoretical calculations suggest the electrical conductivity can be reduced by Y doping, which might be one underlying reason for low power consumption. Furthermore, it is found that Y also shows an advantageous role in tuning the band structure and triggering the indirect to direct band gap transition in Sb-Se system, which is of great importance for the design of optoelectronic devices. Thus, our work indicates the important role of Y dopant in Sb-Se system for both phase change memory and other semiconductor devices.