The 0Cr18Ni9 stainless steel film with a thickness of 20 μm was ablated and cut in a micro-machining. Firstly, the ablation threshold of 0Cr18Ni9 stainless steel film and the beam waist radius of a femtosecond laser were obtained based on the functional relationship between ablation area and laser energy. Then, the metallographic phase and electrical resistivity of the stainless steel film ablated by the femtosecond laser were researched in detail to observe the heat effect caused by the laser. Finally, in order to research the effect of femtosecond laser ablation on the phase composition of the stainless steel film, specimens were tested by X-ray Diffractometry(XRD). Experimental results demonstrate that the waist radius of femtosecond laser is 10.416 μm and the ablation threshold of the stainless steel film with a thickness of 20 μm is 0.455 J/cm2. The metallographic phase of specimens cut by the femtosecond laser is in a recovery process, and its metallographic phase is not changed. The phase composition of stainless steel film is not affected by the femtosecond laser cut, however, the content of phase has been changed.