In order to study the flow field distribution and droplet/particle behavior in two-stage suspension high-velocity oxygen fuel spraying, three-dimensional Euler-Lagrange coupling modeling method was used to simulate the flow field and the process of suspension fragmentation atomization, motion heat transfer, evaporative diffusion and finally being captured by substrate. The suspension properties are compiled by an experiment-based fitting function and the influence of droplet shape changes is considered. The results show that: By adjusting the mass flow rate of nitrogen, the flame flow temperature can be adjusted without affecting the flame flow velocity, so as to meet the technological requirements of coating preparation of different temperature-sensitive materials. By adjusting the volume flow rate of suspension, the suspension can reach the center of flame flow and be heated and accelerated sufficiently. Appropriately reducing the volume flow rate of suspension is helpful to improve the temperature and velocity of particles captured by substrate, appropriately increasing or decreasing the particle concentration of suspension can increase the particle output per unit time or reduce the particle size without affecting the velocity of particles captured by substrate, which can be adjusted according to different process requirements.