Objective To determine risk factors of postoperative pulmonary complications within 1 month in patients undergoing thoracic surgery in Day Care Unit. Methods The total of 200 patients routinely scheduled for VATS under centralized management were enrolled in this study. On the postoperative day 1， lung ultrasound （LUS） was conducted by one physician in the ward. The patients received at least once Chest X?ray or CT in outpatient department within 30 days after discharge. The composite of out?of?hospital PPCs， and the value of LUSS in predicting the PPCs was appraised. Furthermore， we identified the perioperative risk factors associated with PPCs in VATS patients. Results Of 200 recruited VATS patients eligible in the Nanjing Drum Tower Hospital， 188 participants received LUS examination and finally completed the 30 days follow?up. Of whom， 68 patients developed the varied types of PPCs. Multivariable Logistic regression analysis indicated that comorbidity of immune system disease（P = 0.021）， lobar resection （P = 0.031） and the postoperative 24 hours LUSS （P = 0.002） were independent risk factors for PPCs within 30 days after VATS. Conclusion Comorbidity of immune system disease，lobar resection and the postoperative 24 h LUSS were independent risk factors for PPCs within 30 days after VATS。