A series of experiments were performed on the fan-shaped water mist interaction with the horizontal under-expanded hydrogen jet flames. The effects of various water mist pres -sures and horizontal release positions were focused on flame length, temperature, and radiant heat flux. The results show that, water mist causes the flame to be tilted and the tilt angle of the flame increases with the water mist pressure, and the horizontal length of the flame is shortened. It is also found that water mist may lead to the radiation and tem-perature enhancement on the axis and downstream of the action position of water mist and flame, which is closely related to the configuration of water mist. However, this sit-uation disappears and the temperature and radiation decrease with the increase of water mist pressure. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.