Liquid atomization is widely used in important scenarios such as internal combustion engines, gas turbines, aero-engines, seawater desalination, heat exchange equipment, and medical equipment. Due to the large difference between the application conditions and the physical properties of the injection object, it is difficult to abstract a general flow field distribution and droplet breakup model. Aiming at the spray "circling" layer and droplet breakup form in the experiment, the Euler-Lagrange multiphase flow model method was proposed to simulate the flow field in the nozzle and the breakup process after injection, to investigate the characteristics of the flow field in the nozzle during the movement of nozzle-needle valve, and to explore the relationship between the velocity distribution of the spray droplets and the flow in the nozzle. The coupled model and the experimental phenomenon have good compatibility in terms of spray characteristics and liquid core structure, as verified by the visualized spray experimental platform built in a low spray pressure environment. The analysis concludes that the internal disturbance of the nozzle plays an important role in the breakup of the spray, and the intensification of the disturbance leads to the more suitable use of the discrete droplet model after the injection.