The aim of this study was to investigate the value of serum Galactomannan (GM) detection for the early diagnosis of Invasive Pulmonary Aspergillosis (IPA) in children as a reference for clinical diagnosis and treatment. A total of 80 high-risk children with IPA were selected (including three confirmed cases, 20 clinically diagnosed cases, 25 suspected cases, and 32 non-IPA patients) for the detection of serum GM concentration by enzyme-linked immunosorbent assay. Confirmed, clinically diagnosed, and suspected cases were set as the IPA group, and the Absorbance Index (AI) value for GM detection in the IPA group was 1.52 ± 0.74, while that in the non-IPA group was 0.57 ± 0.23; the difference was statistically significant (t=7.03, P<0.05). When the AI value for GM detection was ≥ 1, the diagnostic sensitivity, specificity, positive predictive value, and negative predictive value were 81.25% (39/48), 93.75% (30/32), 95.12% (39/41), and 96.92% (30/39), respectively; when the AI value of GM detection was ≥ 0.5 and positive, the diagnostic sensitivity, specificity, positive predictive value, and negative predictive value were 91.67% (44/48), 75.00% (24/32), 84.62% (44/52), and 85.71% (24/28), respectively. The positive cutoff value of the GM test had the strongest effect on detection accuracy. When the positive cut-off value was 1.0, the diagnostic sensitivity and specificity increased.