Objective To evaluate the creditability of warning message of white differential count (WDF) and white precursor cell (WPC) channels in Sysmex XN-3000 hematology analyzer,and verify its optimal threshold and adjust the alarm threshold.Methods A total of 61 EDTA-K2 anticoagulated blood samples without abnormal warning and 521 EDTA-K2 anticoagulated blood samples with abnormal warning were simultaneously detected in WDF and WPC channels.After the smear specimens of blood sample were automatically prepared by the instrument,microscopic examinations were performed manually.The results of microscopic examination were considered as the gold standard to determine the reliability of the warning message from the instrument and verify the reasonability of initial warning threshold value provided by the manufacture.Consequently,the threshold values were adjusted based on the requirements in practical work.Results The warning messages of atypical lymphocytes and blasts/abnormal lymphocytes in WDF channel were higher sensitive (95.8％ and 100％ respectively),but lower specific (34.7％ and 23.5％ respectively) compared with microscopic examination.The warning messages of atypical lymphocyte,blasts and abnormal lymphocytes in WPC channel were lower sensitive (81.3％,66.7％,and 76.5％ respectively) but higher specific (61.9％,55.5％ and 88.3 ％ respectively) compared with microscopic examination.According to the ROC curve analysis,the prognostic values of warning message of microscopic examination were of medium level,except the warning message for abnormal lymphocytes was poor compared with WPC channel.Combining the practical retest rules,the optimal critical threshold values of atypical lymphocytes and blasts/Abn lymph in WDF channel were adjusted as 120,and they were adjusted as 140 in WPC channel.Conclusion The high sensitive WDF channel should first be used for screening,and the detectable warning message could be retested by using high specific WPC channel to shorten the turnaround time of the test results and improve the working efficiency.The initial critical warning threshold provided by the manufacture should be verified and adjusted to the optimum critical threshold in order to ensure the accuracy of test results.