Objective： To investigate the clinicopathological features and prognostic factors of invasive mucinous adenocarcinoma （IMA）of the lung. Methods：From January 2015 to December 2019，106 patients were identified as having IMA accepted radical resection and enrolled in the retrospective study. Their clinicopathological features were analyzed，the overall survival rate and disease-free survival rate were calculated by Kaplan-Meier and log-rank test，and the survival curve was generated. Results：On preoperative CT images, 14 patients showed pneumonia. All patients received radical surgery，and 50 patients received postoperative adjuvant therapy. Univariate survival analysis showed that pneumonia type，T stage，lymph node metastasis and whether adjuvant treatment were the factors affecting the overall survival rate of IMA patients（P < 0.05）. In addition, the expression of pneumonia，T stage，lymph node metastasis，operation method and whether adjuvant treatment were related to the disease-free survival rate（P < 0.05）. Multivariate survival analysis of Cox risk assessment model showed that pneumonia and lymph node metastasis were independent risk factors affecting the overall survival rate and disease-free survival rate of IMA patients（P < 0.05）. Conclusion：The manifestation of pneumonia and lymph node metastasis are associated with the poor prognosis of IMA.