As referred to the laser diode with wavelength stabilization and linewidth narrowing required in pumping Cesium vapor lasers, volume Bragg gratings are employed as the external cavity output mirror and the effect of volume Bragg gratings with different diffraction efficiencies on output spectrum of external cavity laser diode is studied. It is demonstrated that the volume Bragg gratings with diffraction efficiencies of 24%, 32% and 37% can improve the laser′s output spectrum apparently. The lasing central wavelength is locked at 852 nm, and the linewidth is narrowed to 0.26 nm. The output wavelength rates of pumping current and operating temperature are less than 10.4 pm/A and 7.2 pm/℃, respectively. With the increase of diffraction efficiency, the external cavity ratio of this system is reduced from 91% to 86%.