Objective To investigate the diagnostic value of the ratio of % Micro to % Hypo in the diagnosis of three kinds of common thalassemia and iron‐deficiency anemia (IDA ) .Methods Forty‐nine cases of IDA ,24 cases of mildα‐thalassemia ,24 cases of mildβ‐thalassemia ,24 cases of silent α‐thalassemia and 120 individuals undergoing healthy physical examination were selected as the research subjects and divided into 6 groups:normal group ,IDA group ,mildα‐thalassemia group ,mildβ‐thalassemia group ,silentα‐thalassemia and mild thalassemia group(in duding mild α‐thalassemia group and mild β‐thalassemia group) .The % Micro and %Hypo were deteced in each group and their ratio was calculated .The results were performed the analysis and comparison .Results The % Micro/% Hypo ratio had statistical difference between the mild thalassemia group and IDA group ,between the mild thalasse‐mia and IDA group with the normal group(P<0 .01) .The% Micro/% Hypo ratio had no statistical difference between the silent α‐thalassemia group and normal group ,and between the mild α‐thalassemia group and mildβ‐thalassemia group (P>0 .05) .With the% Micro/% Hypo ratio of 0 .9 as the discriminant value to diagnose mild thalassemia and IDA ,its sensitivity ,specificity and accuracy for diagnosing mild thalassemia were 91 .67% ,91 .89% and 91 .72% respectively ,the sensitivity ,specificity and accuracy in diagno‐sing IDA were 91 .94% ,91 .25% and 91 .18% respectively .Conclusion The ratio of % Micro/% Hypo has good differential diagno‐sis and assisted diagnosis screening value ,but has little value for diagnosing silent α‐thalassemia .