Objective To explore the effect of 16F gastric tube on pain relief in postoperative lung cancer patients. Methods A total of 118 lung cancer patients were treated with radical resection of lung cancer in our hospital between January 2015 and May 2016. The patients were assigned into two groups: a 16F gastric tube group (16F group, 60 patients, 30 males and 30 females at age of 41-73 (52.13±7.83) years and a 28F drainage tube group (28F group, 58 patients, 25 males and 33 females at age of 45-75 (55.62±4.27) years. Clinical effects were compared between the two groups. Results There was no statistical difference in drainage time (4.47±1.03 dvs. 4.24±1.16 d, P=0.473), drainage amount (560.37±125.00 mlvs. 656.03±132.45 ml, P=0.478), incidences of pneumothorax (5/60 vs. 2/58, P=0.439), pleural effusion (6/60 vs. 3/58, P=0.522), and subcutaneous emphysema (3/60 vs. 1/58, P=0.635) between the two groups (P>0.05). The pain caused by the drainage tube in the16F group was less than that in the 28F drainage tube group with a statistical difference (F=4 242.996, P<0.001). The frequency of taking analgesics in the 16F group was significantly less than that in the 28F group (12/60vs. 26/58, P<0.001). Conclusion The effects of draining pleural effusions and promoting lung recruitment are similar between the 16F group and the 28F group. However, the wound pain caused by 16F gastric tube is significantly less than that by 28F drainage tube.