Objective To observe the expression of Myc associated factor X (MAX) in aortic dissection tissue, and to discuss its biological functions. Methods MAX expression level was evaluated by qRT-PCR and Western blotting analysis in 15 dissected aorta samples. The adenovirus vector was used to transfect human aortic smooth muscle cells (HASMCs) for overexpression of MAX. The effects of MAX overexpression on proliferation and apoptosis of HASMCs were analyzed by Cell Counting Kit-8 and flow cytometry, respectively. Results MAX mRNA and protein expression levels were significantly higher in the aortic dissection tissue compared with that in the healthy controls. Overexpression of MAX significantly inhibited the proliferation of HASMCs and promoted its apoptosis (P<0.05). Conclusion MAX might induce the loss of HASMCs via regulating their proliferation and apoptosis process, thus play an important role in the development and progression of aortic dissection.