Abstract: In order to overcome disadvantages of a free-space self-mixing system,such as short working distance and susceptivity to the environment,an all-fiber self-mixing interference system was designed using a fiber to transmit light and a gradient refractive index(GRIN)lens to collect feedback light.The collection efficiency model of the GRIN lens with a mirror reflecting surface was built.Then the feasibility of an all-fiber self-mixing interference system was theoretically proved.Finally,the experimental facility was established.Experiments were carried out with aluminous foil as reflecting surface.The experimental results show that this new instrument can acquire fine signal and it also has the ability of remote measurement.