Absorption auto-cascade condensation combined oil gas recovery system and recovery method

The invention discloses an absorption auto-cascade condensation combined oil gas recovery system and recovery method. The oil gas recovery system comprises an oil gas compressor, an absorption tower,a shallow cooling stage, a cryogenic stage evaporator, a shallow cooling stage, a cryogenic stage condenser, a refrigeration compressor, an oil collecting tank and a monitoring system; wherein the oil-gas compressor is sequentially connected with the absorption tower, the shallow-cooling-stage evaporator, the copious-cooling-stage evaporator, the shallow-cooling-stage condenser and the copious-cooling-stage condenser; the absorption tower is sequentially connected with a shallow-cooling-stage evaporator, a deep-cooling-stage evaporator and an oil collecting tank; and the monitoring system comprises a control module for monitoring the liquid level signal of the absorption tower, the liquid level signal of the oil collecting tank and the evaporation temperature of the system. According to the oil gas recovery method