Objective：This stndy aims to investigate the expression and function of long non-coding RNA（lncRNA）TPTEP1 in lung adenocarcinoma. Methods：Eighty-six pairs of lung adenocarcinoma patients’ tumor and adjacent-tumor tissue samples，33 pairs of preoperative and postoperative plasma samples from lung adenocarcinoma patients were collected，and qRT-PCR was used to detect the expression of TPTEP1. The correlation between TPTEP1 levels and clinical features were analyzed. After using lentivirus to overexpress the expression of TPTEP1 in lung adenocarcinoma cell lines A549，CCK-8 and tranwell experiments were used to evaluate the proliferation，invasion and migration ability of lung adenocarcinoma cells. Results：The expression of TPTEP1 in lung adenocarcinoma tissues and cell lines was significantly lower than that in the control group，and its expression was significantly related to the tumor size，tumor differentiation，lymph metastasis and TNM stage of lung adenocarcinoma. Overexpression of TPTEP1 significantly inhibited the proliferation，invasion and migration of lung adenocarcinoma cells. Conclusion：The expression of TPTEP1 in lung adenocarcinoma tissue and preoperative plasma is significantly reduced，and it could inhibit the proliferation and metastasis of lung adenocarcinoma cells，which might provide a feasible potential target for the diagnosis and therapy of lung adenocarcinoma.