Abstract: Concrete-filled steel tube (CFST) is widely used in engineering because of its high strength, good ductility and strong stability. Under the influence of material performance degradation and external loads, the performance of concrete-filled steel tube continues to deteriorate; but during its service, the use of damage methods to cut the outer steel tube to detect the deterioration of the internal concrete is often not allowed, therefore, the use of non-destructive testing methods to monitor concrete-filled steel tube under different stress states is necessary. In this paper, the failure processes of two kinds of concrete filled steel tube specimens, ordinary and hollow sandwich, were respectively monitored by ultrasonic under axial load. Based on the sensitivity of coda wave to small changes in the medium, a coda wave damage index, coda wave travel time deviation change rate, was constructed which is suitable for damage monitoring of concrete filled steel tube members. The results show that ultrasonic signal amplitude, coda wave travel time deviation and coda wave travel time deviation shift rate can effectively reflect the damage evolution of concrete-filled steel tube (CFST), and the three indexes all decrease significantly before the failure of the specimen. Compared with ordinary concrete-filled steel tube specimens, the mutation points of the three damage indexes of concrete-filled steel tube with inner tube are later, which confirms that the ductility of concrete-filled steel tube with inner tube is better. Compared with the abrupt points of ultrasonic signal amplitude and coda wave travel time deviation, the abrupt points of the change rate of coda wave travel time frequency shift are closer to the occurrence point of the ultimate bearing capacity of CFST, so it is more suitable to be used as an early warning index of the failure precursor of CFST members.