Abstract: [Objective] This study aimed to analyze the dynamic changes in serum metabolites of dairy cows within 7 days postpartum,revealing their metabolic adaptation mechanisms and potential health risks,thereby providing a scientific basis for optimizing postpartum management. [Method] Serum samples were collected from 5 dairy cows at 1,4,and 7 days postpartum. Nuclear Magnetic Resonance（NMR） metabolomics technology combined with multivariate statistical analysis（PCA,OSC-PLS） was used to screen key differential metabolites,and their biological significance was integrated through metabolic pathways. [Result] The results showed that postpartum fat mobilization was enhanced,with significant increases in 3-hydroxybutyrate and acetone,indicating a risk of ketosis, glucose continued to decline,associated with increased demand for lactose synthesis, acetate and lactate increased,reflecting rumen fiber fermentation recovery and potential subacute acidosis risk,respectively, glycine and citrate initially increased and then decreased,participating in oxidative stress regulation and energy homeostasis transition,respectively. Further analysis revealed that postpartum metabolism in dairy cows exhibited a phased characteristic of fat mobilization-rumen recovery-milk component synthesis. [Conclusion] Based on these findings,it is recommended to implement strategies such as dietary optimization（increasing readily fermentable carbohydrates (35~40%) and balancing fiber）,ketosis monitoring（blood ketone testing）,and functional additives（e.g.,rumen-protected choline） to alleviate negative energy balance and ensure lactation performance. This study provided a metabolomics basis for precise nutritional interventions in postpartum dairy cows.

Key words: dairy cow, postpartum metabolism, metabolomics, ketosis, negative energy balance