The invention provides a high-resistivity silicon-based bimetallic gate terahertz polarization chip and a preparation method. A layer of ultraviolet film with a high and low scattered grid structure is arranged on a high-resistivity silicon substrate; and a metal film is compounded on the upper surface of an ultraviolet film. Through adoption of the high-resistivity silicon substrate, the defectsof an existing terahertz polarizer on a supporting structure is overcome, and the terahertz polarizer develops from a terahertz polarization thin film which needs frame support to a terahertz polarization chip with very high structural stability and reliability. The high-resistivity silicon-based bimetallic gate terahertz polarization chip is prepared by a standard ultraviolet nanoimprinting process and a micro-mechanical electronic system (MEMS) process. The preparation process is mature and reliable, and can be applied to large-scale manufacturing of high-resistivity silicon-based bimetallicgate terahertz polarization chips.