a dual-wavelength fiber ring laser with FBGs in series and its active sensing by extracting a single wavelength and adding feedback to the system are presented.The principle of the dual-wavelength fiber laser with gain competition among the applied channels and the output power with optical feedback are theoretically analyzed.We demonstrate this system for the measurement of the movement of vibrational targets and investigate the effect on output signals under different feedback conditions.The experimental results show that this system has the same sensitivity as the self-mixing interference,the direction of the movement can be distinguished from the inclination of the fringes,and we can get information of the feedback targets from the output signals.