<p>The investigation of the tectonic deformation characteristics at the front margin of the Xu–Su arc tectonic belt provides important reference points for identifying and analyzing its genetic mechanism, tectonic evolution process, and the latest evidence of tectonic deformation. In this study, two reflection seismic exploration profiles across the front margin of the Xu–Su arc tectonic belt are utilized to reveal that the Qinglongshan fault is the thrust fault of its front margin boundary. The kinematic properties and tectonic deformation characteristics of the internal faults in the front margin basin are also obtained. Using the Qinglongshan fault as the boundary, the middle and posterior margins of the Xu–Su arc tectonic belt are composed of numerous thrust faults, which suggest strong ancient tectonic movement. However, a large number of normal faults are developed within the front margin basin, with some faults exhibiting strike-slip and growth properties, which indicate strong neotectonic movement. Results reveal that the Xu–Su arc tectonic belt is a large-scale thrust-nappe structure that has undergone structural inversion. The Xu–Su arc tectonic belt experienced strong tectonic activity during the Middle Pleistocene, and the most recent tectonic deformation has extended into the front margin basin interior.</p>