To study the dynamic response of square recycled aggregate concrete-filled steel tube (RACFST) columns under explosion loads, explosion examinations and numerical analyses were performed. Based on the measured longitudinal strain and residual displacement of the columns, the effects of recycled aggregate replacement percentage, steel tube thickness, explosive charge weight, blast center distance, and explosion height on the dynamic response of square RACFST columns are analyzed, and the failure modes are investigated. Then, the established numerical model was verified through test results, and further explore the dynamic response of square RACFST columns. It indicates that square RACFST columns suffer localized damage after detonation, and no obvious global deformation occurs. The localized failures, including blast pit, steel tube bulge or rupture, and weld fracture, could be observed on these columns. The square RACFST columns strain and displacement values are positively correlated with TNT equivalent and RA content, while negatively correlated with steel tube thickness and blast center distance. Furthermore, the concrete absorbs most of the total energy, implying the important role of core concrete in the explosion resistance of RACFST columns.