Carbon dioxide curing was adopted to accelerate the hydration of foam concrete samples with a lower bulk density level of around 450 kg/m3 and a higher level of around 1150 kg/m3. The bending strength, compressive strength and ultrasonic transmission velocity of carbonated harden foam concrete were tested, the hydration products were analyzed by means of XRD and TG/DSC. The results show as: (1) By comparing with standard curing samples, there are more than 47% increments of specific strengths of carbonated foam concrete with the higher density level at a certain curing time before 14d. However, for the lower density level one, there is just a significant improvement of specific bending strength obtained before 7d. (2) The carbonated foam concretes with the lower density level show lower ultrasonic transmission velocity than standard curing ones. The velocities have hardly difference for both carbonated and standard curing samples with the higher density level. (3) Vaterite can’t be found in carbonated foam concrete with the lower density level at curing time before 28d, while it becomes a common phase in 3d’s carbonated sample with the higher density level. Vaterite was considered to be an important factor that influences the ultrasonic transmission velocity.