Objective To investigate the early diagnostic value of HRCT combined with GM test for pulmonary aspergillosis infections in immunocompromised patients. Methods 96 immunocompromised patients who suspected to suffer invasive pulmonary aspergillosis had been collected, and divided into two groups after diagnosed, including infection group (39 cases) and non-infection group (39 cases). HRCT scan was used to analyze the signs of pulmonary CT. At the same time, GM test was used to detect the content of galactomannan in patients, which were divided into positive and negative cases. Statistics of lung HRCT and serum GM test alone and combined diagnostic sensitivity, specificity, positive predictive value of invasive pulmonary aspergillosis and negative predictive value. Results Sensitivity, specificity, positive predictive value and negative predictive value of invasive pulmonary aspergillosis diagnosed by HRCT are 66.7%, 87.7%, 78.8%, 73.5%. Serum GM test, respectively, 82.1%, 91.2%, 86.3%, 88.1%; The HRCT and serum GM tests parallel connection, respectively, 94.5%, 82.5%, 78.7%, 96.0%. HRCT and serum GM test series connection, respectively, 61.5%, 94.7%, 88.9%, 78.3%. Conclusion Relative to HRCT and serum GM tests used alone to diagnosis of secondary IPA of immunocompromised patients, Sensitivity and negative predictive value of HRCT and serum GM test parallel analysis are higher, and the specificity and positive predictive value of tandem analysis were higher, so the combined use of HRCT and GM tests was beneficial to improve the diagnostic efficacy.