A loop tower CO2 capture system includes a feeding unit, a carbonator, an accumulator, a calciner, a combustion chamber and a gas blower. The feeding unit has a first gas pipe. The carbonator includes multiple first cyclone dust collecting units. The first gas pipe has one end connected to the uppermost first cyclone dust collecting unit. The accumulator is connected to the lowermost first cyclone dust collecting unit, and is located between the carbonator and the calciner. The calciner includes multiple second cyclone dust collecting units. The accumulator is connected to the uppermost second cyclone dust collecting unit. The first gas pipe has the other end connected to the lowermost second cyclone dust collecting unit. The combustion chamber is connected to the lowermost second cyclone dust collecting unit. The gas blower is connected to the first gas pipe of the feeding unit.