Abstract: Objective: To investigate the safety and clinical effectiveness of microwave tissue coagulation(MTC) by fiberoptic bronchoscopy in treating central lung cancer.Methods: The canine respiratory was observed after microwave of various energy fire the wall of bronchus.The recovery of injury and pathological changes were observed under light microscope and electron microscope after canines were killed from 1 to 8 weeks.Lung cancer patients(n=90) with atelectasis and dyspnea were devided into two groups.One group was treated with MTC and chemotherapy(treatment group),the other group was treated only with chemotherapy(control group).The alleviating of symptom and change of X ray were observed.Activity of natural killer cell(NK cell) and lymphocyte blastagensis test(LBT) were detected.Results: All canine respiratory and the injury of bronchus were recovered quickly.Dyspnea of some cases was alleviated,activity of NK cell was elevated significantly(P<0.01) and atelectasis of patients were reinflated completely in 35 cases,reinflated partially in 8 cases in treatment group.Atelectasis of 8 cases were incompletely inflated in control group.Conclusions: MTC treatment in central lung cancer is safe and effective.MTC treatment can alleviate symptoms of airway obstruction and enhance immunity.