Background: The brain is one of the most vulnerable metastasis sites in lung cancer; approximately 40–50% of lung cancer patients develop brain metastasis during the disease course, contributing to the poor prognosis and high mortality of lung cancer patients. Therefore, it is important to clarify the molecular mechanism underlying brain metastasis of lung cancer for improving the overall survival of lung cancer patients. The present study aimed to investigate the potential role of blood-brain barrier (BBB) permeability in the development of brain metastasis of lung cancer and explore the effect of aspirin in an in-vitro BBB model. Methods: An in-vitro BBB model was established. The expression of heat shock protein 70 (HSP 70), zonula occludens-1 (ZO-1), and occludin in rat brain microvascular endothelial cells was detected using Western blot at different time points following the administration of aspirin. Results: HSP70, ZO-1, and occludin expressions did not show significant changes before aspirin administration, but increased noticeably after aspirin administration. Tumor necrosis factor-\alpha (TNF-\alpha) could significantly attenuate the increased expression of these proteins induced by aspirin. Additionally, TNF-\alpha also significantly reversed the aspirin-induced decrease of BBB permeability. Conclusions: Aspirin may inhibit brain metastasis of lung cancer in a time-dependent manner via upregulating tight junction proteins to reduce BBB permeability, and this effect can be reversed by TNF-\alpha.