Abstract: In order to optimize the parameters and improve the quality of laser drilling, the experiment and theoretical analysis of laser drilling on SUS304 stainless steel with 5mm thickness was conducted based on the orthogonal experiment method. The inlet aperture, outlet aperture and hole taper of laser drilling were measured and calculated respectively. The effect degree of the parameters, such as pulse width, pulse energy, repetition frequency, defocusing amount and pulse number, on the hole taper was gotten. And the optimal parameters combination of laser drilling on SUS304 were obtained. The results show that defocusing amount, pulse width and pulse number have a great effect on hole taper, while repetition rate and pulse energy have a little effect on hole taper. The optimized laser parameters are pulse width of 0.5ms, pulse energy of 2.5J, repetition frequency of 40Hz, defocusing amount of 0mm and pulse number of 200.The smallest taper can be obtained with the optimized laser parameters.