The invention discloses a preparation device of a gallium nitride film, and particularly relates to the technical field of gallium nitride film preparation. The preparation device of the gallium nitride film comprises a preparation bin and an evaporation chamber, the evaporation chamber is fixedly connected to the bottom end of the interior of the preparation bin, a quartz crucible is fixedly connected to the interior of the evaporation chamber, an electric heating wire is fixedly connected to the interior of the quartz crucible, an ionization cavity is fixedly connected to the top end of the evaporation chamber, and a heat preservation structure is arranged on the outer side wall of the preparation bin. According to the preparation device of the gallium nitride film, an cavity, a shell, a connecting rod, a nut, a through hole and heat preservation rock wool, during use, the shell is fixed to the exterior of the preparation bin by utilizing the nut and the through hole, at the moment, the cavity is formed between the preparation bin and the shell, then the interior of the cavity is filled with the heat preservation rock wool, the heat insulation performance of the heat preservation rock wool is utilized, and therefore, rapid loss of heat in the interior of the preparation bin can be avoided, then the temperature in the interior of the preparation bin can be kept stable, and the preparation quality of the gallium nitride film is improved.