In this paper, a narrow-band tunable external-cavity semiconductor laser with the Littman set-up is reported. The laser system consists of a semiconductor laser, a blazed grating and an external mirror. Its sideband suppression ratio over 20 dB was obtained. Conveniently tuning in wavelength region of 797.38-807.26 nm was achieved. The laser is operating in single frequency with narrow linewidth smaller than 0.06 nm. The output beam has good directional stability when tuned.