In order to solve the problems of microcracks in high pulse energy femtosecond laser drilling,a trepanning method with femtosecond laser was proposed.The femtosecond laser with pulse width of 120 fs was used to trepan 304 stainless steel with 0.5 mm thickness.The effect of defocusing amount and relative deflection angle of double wedge on the micro-hole diameter and the effect of defocusing amount on the micro-hole conicity are studied by the experiments.The results show that the diameters of micro-holes increases with the increasing of the defocusing amount,but the conicity first decreases and then increases.When the defocusing amount is zero,the minimum conicity is 3.5°.Micro-hole diameter increases with relative deflection angle increase of double wedge.Nanometer periodic stripes are found on the sidewalls of micro-holes trepanned by femtosecond laser,while there are microcracks on the sidewalls of micro-holes through percussion drilling.