The reasonably simplified physical model based on actual once-through steam generator is used as the fluid domain, and the influences of droplet diameter, droplet axial velocity, droplet radial disturbance and critical quality are fully considered in the present work. Then the heat transfer characteristics of dryout and post-dryout mist flow region are investigated based on Euler-Lagrange method. The results show that present model and method can be used to accurately model the influences of dryout parameters on post-dryout heat transfer. The decreasing droplet diameter leads to a decrease in the maximum value of soaring wall temperature in post-dryout developing region. With the increasing droplet axial velocity, the axial wall temperature gradually transforms from a decrease trend into an increase trend, and the influence on the wall temperature and heat transfer coefficient can be neglected after it reaches 5 m/s. The increasing droplet radial disturbance leads to a decrease in the maximum value of soaring wall temperature. Low critical quality helps to reduce the deviation level from thermodynamic equilibrium. The overall wall temperature in the case with droplets decreases by about 39 K compared to that in the case without droplets, and the heat transfer performance caused by droplet and its control parameters can be enhanced by 60% within present operating range. (C) 2018 Elsevier Ltd. All rights reserved.