To solve limitations of existing terahertz radiation in the tunable range of output frequency and output power, it started from Maxwell's equations of nonlinear medium to analyze the optical properties of the nonlinear polymer theoretically, and a mathematical model of silicon waveguide configuration was established. The high refractive index of silicon was used to design the silicon terahertz waveguide. It also analyzed the mode map of terahertz waveguide, and discussed the effective index, waveguide loss, and the relationship between continuous-wave’s output power and output frequency of silicon terahertz waveguide mode. The experimental results show that terahertz generated from silicon terahertz waveguide is tunable in the range of 0.1 THz to 15 THz continuously at room temperature, and its output power can reach several micro-watts.