Abdominal aortic aneurysm (AAA) is characterized with progressive weakening and considerable dilation of the aortic wall. Despite the high risk of mortality in the elderly population, there are still no clinical pharmacological therapies to alleviate AAA progression. Macrophage-derived MMP9 acts as a key factor in extracellular matrix degradation and is crucial for aortic aneurysm development and aortic rupture. Here, we demonstrated that the transcription level of MMP9 was suppressed with a concentration-dependent manner in macrophages after Imatinib treatment, which was accompanied by the down-regulation of MMP9 protein expression and reduced MMP9 secretion in vitro. Imatinib administration (50 mg/kg/d, i.g.) was carried out one week after the establishment of elastase-induced AAA in rats, stabilizing aneurysm progression and improving survival rate via decreasing the aortic diameter and preventing elastin degradation. Expression and activity of MMP9 in the artery tissues were significantly suppressed after Imatinib treatment via in situ assessment like immunohistochemistry and zymography, although macrophage infiltration was not affected. Furthermore, we found that Imatinib inhibited MMP9 transcription through reduction of STAT3 phosphorylation and translocation from nucleus to cytoplasm. These observations indicated that Imatinib prevents aneurysm progression by inhibiting STAT3-mediated MMP9 expression and activation, suggesting a new application of Imatinib on AAA clinical therapy.