The JT3 Cell Counter produced by Coulter Company can give out differential results when analyzethe whole blood cells.We detected 258 venous anticoagulated blood samples from clinic patients,compared theJT3 results with that of manual microscopic method.The coefficients of iymphcyte and granulocytc arc 0.951 and0.930.That of monocyte is 0.468.For the eosinophile and basophile,the instrument can give quanlititaveresults,the precision is good.It also can show positave flags for the abnormal samples.The positive rate is 22%(32% true Positive).The false negative rate is 0.5%.The JT3 Cell Counter is easy to operate,the defferential re-sult can be used as a screening method for the blood rountine test.