Abstract： Objective To verify the linear range of the platelets at Bayer ADVIA 2120 analyzer. Methods According to ISO15189 EP6-A,platelet separated from 250 samples to verify the linear range at Bayer ADVIA 2120 analyzer. Results High concentrations of platelet can obtained from mixing multi samples. Coefficient of Variance of within-run and between-day was 3.0% and 3.6%, carry-over was 0.02% ,platelet range at 21-4918 × 109/L Showed a linear relationship. Conclusion Regardless of blood type, high concentrations of platelet can obtained from mixing multi samples. Bayer ADVIA 2120 automated hematology analyzer has good feafures of precision ,linearity ,low carry-over, is a perfect performance analyzer.