Indium phosphide (InP)-based high electron mobility transistors (HEMTs) have been widely adopted in space communication systems such as satellites, manned spaceflight, and deep space exploration due to their high frequency and gain, and low noise. However, high-energy particles such as protons, electrons, and neutrons in a space environment affect the performance of InP-based HEMTs and reduce the reliability of space communication systems. This paper mainly discusses the influence and degradation mechanism of defects induced by high-energy particle irradiation on the direct current (DC) and radio frequency (RF) performance of InP-based HEMTs, as well as the transconductance and kink effect in the irradiation environment. Subsequently, the research progress of radiation-hardening measures for InP-based HEMT devices is summarized and analyzed so as to provide the theoretical guidance for studying damage mechanism of InP based HEMT irradiation effect and improving its radiation-hardening technology. Finally, based on current challenges in the field, future research directions are proposed for radiation effects and radiation-hardening technologies of InP-based HEMTs.