Abstract: Objective To analyse the critical value of hemoglobin for assessing iron deficiency anemia(IDA)of women aged 20～45 years old sampled from the Survey of Chinese Nutrition and Health(CNHS)in 2002.Methods Concentration gradient of Hb was designed to establish the critical value of Hb according to other indexes' changes trend and the meanings of indexes in the process of iron deficiency.Results Hb concentrations correlated with other iron assessing indexes significantly (P<0.01).The cut-off values of Hb in diagnosing IDA were 115 g/L for child-bearing women aged 20～45 years old.Conclusion The cut-off value of Hb in diagnosing IDA for Chinese child-bearing women aged 20～45 years was 5 g/L lower than that of WHO/UN ICEF.