In the present study the authors performed surface treatment of stainless steel 65Mn (the thickness is 60 μm) by femtosecond laser (pulse duration 148 fs, wavelength 775 nm). The single-pulse threshold could be obtained directly to be about 0.2 J·cm-2. The authors found that the femtosecond laser produced a large number of micro-structures such as nano-pores and nano-protrusions. Then the authors discussed the influence of pulse power and the number of shots on the formed surface structures. The authors found that with the change in the power and the number of pulses, the period of multiple parallel grooved surface patterns remained unchanged, which is about on the sub-micron level. Finally the authors processed the array of holes and the lines with different speed and number of pulses.