A Fabry-Perot (F-P) interferometric fiber sensor based on femtosecond laser direct writing is designed to achieve dual parameters measurement of displacement and external strain,and the implementation principle of the sensor is studied and experimentally verified.First,a femtosecond pulsed laser is used to inscribe two lines of length 48 μm in the longitudinal direction of the core of a standard single mode fiber (SMF) with a spacing of 105 μm to form an F-P resonant cavity,and then one end of this structure is cut flat to form a composite interferometer together with an all-reflective mirror,thus constituting a displacement sensor.The cut flat end is then knotted to allow for stress measurements again.The experimental results show that the displacement sensitivity of the structure at the Dip1 position is －440.3 pm/μm with a linear fitting coefficient of 0.990 3;the strain sensitivity at the Dip2 position can be measured after the structure is knotted at 1.2 pm/με with a linear fitting coefficient of 0.992 4.The sensor is simple to fabricate,low cost,tiny structure,good linearity and easy to repeat.The sensor is of practical value in both displacement sensing and strain sensing fields.