Abstract: The circulators and the isolators with ferromagnetic substrates are essential components for the satellite sub-millimeter and terahertz communication systems, which can protect the emission channel from the damage of high power reflection. This paper proposes a novel design of the terahertz circulator, based on the photonic crystals. The photonic crystals are made of several rows of high-permittivity dielectric rods, and they can be used for the terahertz wave guiding with a small conducting loss. In the space radiation environment, the internal charging characteristics of the photonic crystals Si and the terahertz crystals are simulated by the electron irradiation with typical energy and fluxes. The simulation results demonstrate that the central frequency, the bandwidth, and the insertion loss of the photonic crystal circulator is 205 GHz, 3 GHz and less than 0.5 dB, respectively, with good spatial adaptability and promising in the space-born terahertz system application.