Provided is a CO2 recovery system including: a high-pressure absorption tower; a high-pressure regeneration tower that partially regenerates a CO2 absorption solution from the absorption tower through a first liquid feed line; a second liquid feed line that extracts a semi-lean solution having a heat resistance temperature thereof or lower from the high-pressure regeneration tower and introduces a portion of the semi-lean solution into a middle stage of the high-pressure absorption tower; a branch line that introduces a rest of the semi-lean solution into a flash drum; a third liquid feed line that introduces a lean solution after adding pressure thereto into a top of the high-pressure absorption tower; a high-pressure CO2 compression device where high-pressure CO2 gas from the high-pressure regeneration tower is introduced; and a low-pressure CO2 compression device where low-pressure CO2 from the flash drum is introduced.