The present invention relates to an acid gas capture system and method which can reduce the energy consumption by using the heat from the system itself of an acid gas capture system. The system and method according to the present invention causes heat exchange to occur between an absorbent discharged from the upper part of an absorption tower of the capture system and a mixed gas comprising an acid gas, and a portion of an absorbent solution which has absorbed the acid gas discharged from the lower part of the absorption tower, and additionally, the remaining absorbent solution excluding said portion thereof undergoes heat exchange with the regenerated high-temperature absorbent solution discharged from the reboiler to preheat the absorbent solution supplied to the regeneration tower, thereby reducing the thermal energy required by same.