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[Objectives] Ketosis is a common metabolic disease found in high-yielding dairy cows. This study aimed to clarify the correlation between ketosis occurrence and the follow indicators by analyzing the data of dairy herd improvement (DHI) and the peripheral blood cell component. [Methods] The cow's production performance data of high-incidence period of ketosis at the first 3 months postpartum were tracked in a large-scale pasture in Jiangsu Province for 3 consecutive years(2018-2020), and 25 healthy and 20 ketotic cows were screened. The peripheral blood of the 45 cows at the first month postpartum in 2020 was selected for further blood cell analysis. The warning effect of each index on ketosis was determined by binary Logistic regression model analysis. And the warning value of each index on ketosis was determined by receiver operating characteristic (ROC) analysis. [Results] The results of dairy herd improvement showed that the milk fat rate had a direct positive relationship with ketosis, and the lactose rate was significantly negatively associated with ketosis. Blood cell analysis of dairy cows showed that the number of lymphocytes and eosinophils were indicators significantly positively associated with ketosis. Further correlation analysis showed that the milk fat rate and the number of lymphocytes had an early warning effect on ketosis. The optimal threshold value of milk fat rate was 4.21% and the optimal threshold value of the number of lymphocytes was 4.815×109 L-1. [Conclusions] The milk fat rate in milk and the number of lymphocytes count can be used as the warning indexes for ketosis in postpartum cows, and can be used to guide the timely regulation and management of dairy farms. [ABSTRACT FROM AUTHOR]