Using the peak power of 600 W thulium-doped fiber laser, the laser pulse parameters were controlled by Labview program to carry out the extracorporeal lithotripsy experiment, and the law of pulsed thulium laser lithotripsy was studied to provide reference for clinical application. The results show that the pulsed thulium laser has good lithotripsy ability. When the pulsed thulium laser with an energy of 0.3 J is set to impact calcium oxalate stones, most of the debris particles are less than 0.5 mm in diameter, which has good pulverization ability. When the pulse energy is small, the gravel efficiency increases rapidly with the increase of pulse energy. For the thulium laser with a peak power of 600 W, the double pulse combination does not produce obvious ‘Moses effect’ to improve the gravel efficiency. In addition, a large pulse width may be set to improve the efficiency of thulium-doped fiber laser lithotripsy. Under this condition, the penetration distance of laser in water is large, reaching 5.4mm in the experiment. Therefore, the safe distance between the fiber end and the surrounding tissue should be fully considered in the operation to avoid damage to the surrounding tissue.