To reveal the volume variation of hardened cement paste with circulating fluidized bed fly ash (CFBFA), CFBFA was employed to replace cement by mass to prepare the cement paste specimens. The volume expansion of the specimens were studied under different curing conditions. Meanwhile, the micro morphology, mineral composition and thermal effect of the CFBFA and paste specimens were analyzed by using scanning electron microscope (SEM), X-ray diffraction (XRD), mercury porosimeter and TG-DSC thermal analyzer. The results show that the water requirement for standard consistency of the blended paste significantly increases with the incorporation of the CFBFA due to the rough and porous surface of the particles. The water requirement for standard consistency of the blended paste with 80% (mass fraction, the same bellow) CFBFA content is 1.6 times as much as that of the neat cement paste. Moreover, the specimens with CFBFA content less than 40% exhibit shrinkage cured under the closed condition, specimens with over 60% CFBFA present remarkable expansion. The internal hydration of the specimens under the standard curing condition are sufficient, the specimens exhibit expansion which increased with CFBFA content under the standard curing condition. The expansion ratio of the specimens with 80% CFBFA content reaches 0.42% after 28 d. All the specimens presented drying shrinkage when they are exposed to the ambient air. However, the specimens with 80% CFBFA content gained more shrinkage over the expansion induced by the inclusion of CFBFA, which is attributed to the higher water to cement ratio.