What is known and objective: To analyse the diagnostic accuracy of bronchoalveolar lavage fluid galactomannan (BALF-GM) assay for invasive pulmonary aspergillosis (IPA) in adults to determine the optimal diagnostic cut-off by meta-analysis.Methods: PubMed, Embase, Web of Science, Cochrane Library, China national knowledge infrastructure (CNKI), and China Wanfang databases were searched to collect relevant studies on the diagnostic value of BALF-GM for IPA from inception to March 2022. The summary receiver operating characteristic (SROC) curve was drawn to determine the optimal diagnostic cut-off.Results and discussion: Nineteen articles (56 data sets) were included. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were 0.79 (95% CI: 0.72-0.84), 0.92 (95% CI: 0.88-0.94), 9.25 (95% CI: 6.84-12.52), 0.23 (95% CI: 0.18-0.30), 39.44 (95% CI: 29.55-52.65), and 0.92 (95% CI: 0.90-0.94), respectively. The area under the curves (AUCs) were 0.92, 0.86, 0.93, 0.89, 0.88, and 0.94 when the cut-off values were 0.5, 0.8, 1.0, 1.5, 2.0, and 3.0, respectively. Sixteen studies were included in the combined analysis when the cut-off value was 0.5. The results showed that the pooled sensitivity, specificity, PLR, NLR and DOR of BALF-GM (cut-off 0.5) for the diagnosis of IPA were 0.89 (95%