Sweep frequency laser source is widely used in optical fiber sensing, computing power network and 50G PON access network, in order to achieve a high quality O-band continuous tunable laser source, the 1 310 nm sweep frequency laser source based on Littman-Metcalf feedback configuration is reported. In this experiment, a gain chip with the reflectance of 0.005% of the curved waveguide end is used as the gain area of the inner cavity, the injection locking of the diffractive laser beam is realized through the external-cavity feedback technology. Experimental results show that under the condition of 500 mA injection current, the tunable wavelength range of 1 270~1 350 nm can be realized with mode-hopping free, the corresponding peak output power is 17.98 dBm, and the sweep power repeatability is about ±0.023 dB.