This invention is applied to the field of terahertz communication and provides a two-path terahertz wave communication system, which comprises a terahertz wave generation module, a terahertz wave transmission channel connected with the output port of the terahertz generation module, and a terahertz wave receiving module connected with the output port of the terahertz wave transmission channel. According to the system disclosed by the invention, one path of optical signal source is converted into one path of horizontally polarized terahertz wave and one path of perpendicularly polarized terahertz wave and then are combined into one path by the terahertz wave generation module for transmission via the terahertz wave transmission channel, and the horizontally polarized terahertz wave and the perpendicularly polarized terahertz wave are re-divided into two paths through the terahertz wave receiving module so as to be received respectively. The two-path terahertz wave communication can be realized, and the rate and the spectrum utilization efficiency of the terahertz wave communication are improved.