In order to study the effect of circulating fluidized bed (CFB) fly ash on the performance of foam concrete, two different CFB fly ash and fly ash (FA) were selected, and the compressive strength, fluidity, pore structure and water absorption of foam concrete were measured. The influences of fly ash content and type on the properties of foam concrete were studied, and the micromorphology and phase composition of foam concrete were characterized by scanning electron microscopy and X-ray diffractometer. The results show that the high sulfur calcium content and irregular particle morphology of CFB fly ash will adversely affect the working performance of foam concrete. When low sulfur calcium CFB fly ash is added, the strength of foam concrete increases with the increase of CFB fly ash content, and the compressive strength of 7 and 28 d reaches the maximum value of 1.30 and 2.25 MPa at 50% (mass fraction, the same below) content. When high sulfur calcium CFB fly ash is added, the strength of foam concrete shows a trend of increasing first and then decreasing with the increase of CFB fly ash content, and the compressive strength of 7 and 28 d reaches the maximum value at 20% and 10% content, which is 1.42 and 2.00 MPa, respectively. The ettringite and C-S-H gel generated during the hydration process of CFB fly ash can fill the pores, increase the proportion of small pores, reduce the porosity, which is beneficial to increase compressive strength and reduce water absorption of foam concrete.