Mountainous environments typically feature diverse terrains. To address the issue of complex signal propagation paths in wireless communication due to terrain obstructions in mountainous areas, a modeling method for terahertz wireless communication under different mountain slopes is proposed. Terrain data is obtained through Digital Elevation Models (DEM), and the ray tracing method is combined with the introduction of a slope factor to analyze the propagation characteristics of terahertz signals in mountainous areas. Simulation experiments are conducted on the received power of the receiver to establish a quantitative relationship between terrain slope and received power. Simulation results indicate that there are significant differences in signal coverage and delay characteristics across regions with different slopes: flatter areas in the mountains generally have more stable signal coverage with a more concentrated power distribution (-172.5~-117.5 dBm); whereas in areas with steep slopes, signal coverage is poor, power distribution is more dispersed, but delay spread distribution is more concentrated (0~3 ns).