Since the Rb vapor′s absorption line varies with the pressure of the buffer gas,it′s essential to make the pumping diode laser′s central wavelength tunable while the linewidth is narrowed with volume Bragg grating(VBG) at the same time.In our research,based on a domestic packaged CS mounted laser,by use of the thermal shift of VBG′s central wavelength,we achieve a tunable diode laser which could be tunable from 779.89 nm to 780.35 nm while the linewidth is no more than 0.3 nm.The diode laser could be used as the pump source of a rubidium vapor laser by means of stack.