The study of liquid jet crushing behavior is of great significance to the safety analysis of nuclear reactors. The particle size distribution formed by crushing is an important factor affecting the combustion rate. In this paper, the computational fluid dynamics code FLUENT is used to carry out three-dimensional simulation calculation of liquid jet breakup. By comparing related test results, the liquid jet trajectory and droplet SMD diameter are in good agreement with the experiment. The applicability of the VOF-DPM model to simulate liquid leakage and breakage behavior is verified. On this basis, the influence of different fluids and different flow rates on liquid jet breakup behavior is analyzed. Studies have shown that when the liquid jet velocity and the pipe fracture diameter are the same, the greater the surface tension of the fluid, the smaller the size of the droplets formed by the breakage; as the liquid jet velocity increases, the average diameter of the resulting particle size decreases; Under the condition of no cross air flow at the orifice, the particle size of the liquid broken is distributed symmetrically along the radial direction. The particle size of the liquid droplet in the center of the jet is smaller, and the particle size near the break in the radial direction is larger.