The high temperature and intricate structure within the low pressure chemical vapor deposition (LPCVD) horizontal reactor chamber can result in uneven temperature distribution when reaction gases are introduced, ultimately influencing the quality of the resulting thin films. To achieve films of superior quality, a physical model of the reaction chamber is developed based on the reactor's equipment data. Using models of heat conduction, heat convection, and heat radiation, finite element simulation software is employed to simulate the multiphysical fields involved in the reaction process, including the flow field, thermal field, chemical reaction field, and dilute substance transfer field. By varying process parameters, such as the gallium source temperature, the simulation assesses the effect of temperature fluctuations within the LPCVD reaction chamber on the deposition characteristics of β-Ga₂O₃ thin films. The simulation results reveal that the uniformity of the films diminishes as the gallium source temperature increases, whereas the deposition rate of the films increases with temperature. Optimal film quality is obtained when the gallium source temperature is maintained between 900 and 950 ℃. By optimizing process parameters, the thickness and uniformity of the β-Ga₂O₃ films grown by LPCVD epitaxy are enhanced, leading to the fabrication of Ga₂O₃ devices with improved performance.