Abstract: To investigate the elastic stress wave propagation in steel-concrete composite structures, a 2 dimensional spectral element model for steel-concrete composite sections was established and the elastic stress wave propagation in the hybrid section with and without interface debonding defects was simulated under single point excitation. The interface debonding was simulated by removing concrete elements between steel tube and concrete core. The wave field and displacement responses of different nodes between the models with and without defects were compared to explain the effect of interface debonding on elastic stress wave propagation. Finally, the displacement responses of different numerical models with different levels of interface debonding were compared to investigate the relationship between the displacement response and the interface debonding defects. Spectral element method (SEM) provides an efficient way for the stress wave simulation of steel-concrete composite structures, which is helpful for the study on the mechanism for interface debonding detection of steel-concrete composite structures based on stress wave measurement.