〔Abstract〕 Objective To explore the clinical diagnostic value of galactomannan (GM) test of alveolar lavage fluid for invasive pulmonary mycosis (IPA). Methods From March 2017 to February 2019, 149 patients with high-risk IPA were admitted to Fujian Provincial Hospital. According to the clinical practice guidelines for aspergillosis and candidiasis developed by the American AntiInfective Society, they were divided into confirmed groups (11 cases), clinical diagnosis group (98 cases), proposed diagnosis group (55 cases), another 67 patients with non-IPA lung disease in the same period were selected as the non-IPA group. The enzyme-linked immunosorbent test (ELISA) was used to detect and calculate the GM index of the patient's alveolar lavage fluid and serum. At the same time, the receiver operating characteristic curve (ROC) was drawn, the GM value in the GM test was greater than the proposed GM cut-off value to diagnose positive, and the clinical efficacy of the alveolar lavage fluid and serum GM index in the diagnosis of IPA was analyzed. Results The alveolar lavage fluid and serum GM index of patients in the diagnosed group and the clinical diagnosis group were significantly higher than those of the proposed group and the non-IPA group, and the alveolar lavage fluid and serum GM index of the confirmed group were significantly higher than those of the clinical diagnosis group. In comparison, the differences were statistically significant (P < 0.05). ROC curve analysis showed that when the diagnostic threshold of alveolar lavage fluid GM index was ≥ 0.37, the sensitivity of diagnosing IPA was 87.50% and the specificity was 81.20%. Conclusion The GMtest of alveolar lavage fluid has the advantages of rapid detection and high sensitivity, and it has high clinical value in assisting the diagnosis of IPA.