The THFR (Tsinghua High Flux Reactor) represents an advanced water-cooled high flux reactor with unperturbed average thermal and fast neutron flux levels reaching 2×10¹⁵ n?cm^-2?s^-1, respectively. This reactor has several outstanding features including high neutron flux, broad neutron energy spectrum, strong irradiation capability, and versatile applications. Its comprehensive irradiation performance is at the international leading level and has important applications in industries, agriculture, aerospace, medical and other fields. This paper firstly analyzes the design characteristics of THFR reactor and related systems, as well as the irradiation application system, including the vessel-in-pool reactor body structure, low neutron self-shielding reactor core design, arc plate type fuel assemblies, rotating control drums, multi-purpose irradiation channel design, and a combination of active and passive safety system design, etc. Then, the application foreground is prospected in the fields of nuclear fuel and material irradiation testing, irradiation production of radioisotopes, neutron science research, etc. THFR provides strong support for serving major strategic needs, safeguarding people's lives and health, and cultivating and developing new quality productive forces.