Abstract： Objective To explore the cut-off value of 50 g glueose challenge test (GCT) for gestational diabetes mellitus (GDM), which is suitable for Chinese women. Methods A multi-centered prospective population-based survey on 16 286 pregnant women, who received 50 g GCT for the first time between Apr. 1, 2006 and Sept. 30, 2006, was performed at 25 hospitls of 18 cities in China. Relative data were retrieved and analyzed. Results Based on the ADA criteria for diagnosis of GDM, the sensitivity and specificity of GCT were 97.9 % and 60. 4 %, 96. 2% and 74.7 %, and 87.0% and 83.1% at a cutoff value of 7. 2 mmol/L, 7.8 mmol/L and 8. 3 mmol/L, respectively. When NDDG criteria for GDM diagnosis was applied, the sensitivity and specificity of GCT were 98.2% and 59.0% respectively at a cut-off value of 7. 2 mmol/L, 96.0% and 73.0% at 7.8 mmol/L and 90. 2% and 81.5% at 8. 3 mmol/L. In diagnosing glucose metabolism disorders (GDM and GIGT), the sensitivity and specificity of GCT were 97. 7% and 61.4%, 95.4% and 75. 8%, and 84.9% and 84.1% at the cutoff value of 7.2 mmol/L, 7.8 mmol/L and 8. 3 mmol/L, respectively. Conclusions A cut-off value at 7. 8 mmol/L for GCT is appropriate for Chinese women.