In order to research the ablation of 0Cr18Ni9 stainless steel films whose thickness is 20μm, stainless steel films were ablated and micro-cut by fs laser in the paper. Firstly, the ablation threshold of 0Cr18Ni9 stainless steel films and the beam waist radius of fs laser were obtained based on the functional relation between ablation area and the laser energy. And, experimental results indicate that the waist radius of fs laser is 10.416μm and the ablation threshold of stainless steel films whose thickness is 20μm is 0.455J/cm2. Secondly, in order to observe the heat-affected zone, metallographic phase and electrical resistivity of stainless steel films ablated by fs laser were researched in detail. And through the experimental results, we can deduce that metallographic phase of specimens which were cut by fs laser was in recovery process and the metallographic was not change. Finally, in order to research the composition of stainless steel films phase affected by fs laser ablation, specimens were tested by XRD. And through the XRD test, it can be deduced the composition of stainless steel films phase was not affected by fs laser cut and the content of phase was affected by it.