The invention provides a coaxial field-biasing type long-wave infrared system based on a spherical reflecting mirror. The coaxial field-biasing type long-wave infrared system comprises a spherical reflecting mirror and a plurality of imaging compensation lens groups with diaphragms, wherein the spherical reflecting mirror and the plurality of imaging compensation lens groups are arranged successively along the light propagation direction. Each imaging compensation lens group with a diaphragm forms one independent imaging channel. The system is a coaxial system; and main light of each channel deviates at a specific view field to avoid mutual shielding of the imaging compensation lens group and the incident light. The plurality of imaging compensation lens groups are distributed at a light emitting part of the concentric spherical reflecting mirror in a fan-shaped manner; and the imaging compensation lens groups and the incident light are not on a same plane. The imaging compensation lens groups include a plurality of short-focus compensation mirrors, a plurality of medium-focus compensation mirrors and a plurality of long-focus compensation mirrors. The plurality of imaging compensation lens groups employ different correction mirror groups with different focuses to correct aberration for different view fields, thereby ensuring a constant high resolution.