During nanosecond pulse laser drilling, recast layer will form along the hole wall, which has a great effect on the quality of nickel-based high-temperature alloy. By considering the heat convection, the heat conduction, and the influence of recoil pressure, surface tension and thermal capillary force, a three dimensional mathematical model of nanosecond pulse laser drilling on nickel-based high-temperature alloy is established. Different pulse parameters of nanosecond pulse laser drilling are simulated when the pulse energy is 24 mJ. The simulated results agree with experimental results. The research shows that the thermal and mechanical effect are all very important to the formation of recast layer. During the drilling process, the temperature of keyhole wall is very high, the maximum of which can reach over 3200 K, and temperature distribution of keyhole wall is not uniform. Besides, recoil pressure is an important factor to cause the melt flow, and the velocity of melt flow caused by recoil pressure is very large, which can come to 60 m/s at peak. Due to the convection of melt in the keyhole′s opening , recast layer in this place is the thickest. Laser width has a great effect on the formation of recast layer, the greater pulse width makes the bigger recast layer thickness, and the greater melt velocity.