To investigate the similarity on thermo-mechanical effects induced by different pulsed beams, and also to give a reference for the experimental research of thermal and mechanical effects under X-ray radiation using simulation method of laser irradiation, the similarity and distinction between impulse coupling with an aluminum target by the pulsed ultraviolet laser(0.308 μm) and X-ray were analyzed. Firstly, the contrast of the mechanism of thermo-mechanical effects between two pulsed beams was compared. Then, a comparative analysis for the quantity of blow-off impulse induced by two pulsed beams coupling with Al materials was performed in lower energy flux (<100 J/cm2) by means of theory and experimental methods. The results show that the generation mechanisms of blow-off impulse are similar in lower energy flux (<100 J/cm2) for the pulsed ultraviolet laser and X-ray, because there are not a phenomenon of plasma shield. The quantity of impulse by these two pulsed beam irradiation has the same order of magnitude of impulse (<102) in same energy flux. Therefore, the two pulsed beam effects are comparable within a certain range.