Objective To analyze the differences in serum amino acid levels between preeclampsia(PE)and normal pregnant women in Urumqi,and to explore the correlation between amino acids with statistically significant differences and PE severity,as well as their diagnostic value for PE patients.Methods A total of 49 normal pregnant women who visited Urumqi Maternal and Child Health Hospital from June 2021 to June 2023 were selected as the control group and 55 PE pregnant women were selected as the PE group,and the PE group was further divided into mild PE group(25 cases)and severe PE group(30 cases).Liquid chromatogra-phy-tandem mass spectrometry technology was used to determine the levels of 25 metabolites in pregnant women's serum.Spearman correlation analysis was used to analyze the correlation between the amino acid lev-els and PE severity.Logistic regression was used to correct for potential confounding factors,and receiver op-erating characteristic curve was used to analyze the diagnostic efficacy of amino acids with significant differ-ences in PE.Results There were statistically significant differences in the body mass index(BMI)and deliv-ery method between the PE group and the control group(P＜0.05).The serum levels of histidine,threonine,glutamine,ethanolamine,methylhistidine,and canine uric acid in the PE group were higher than those in the control group(P＜0.05).The serum levels of threonine,glutamine,methylhistidine,and canine uric acid in the severe PE group were higher than those in the mild PE group and control group(P＜0.05).The serum ethanolamine levels in the mild group and severe PE group were higher than those in the control group(P＜0.05).The serum histidine levels in the severe PE group were higher than those in the control group(P＜0.05).Correlation analysis showed that serum glutamine,ethanolamine,methylhistidine,and canine uric acid were positively correlated with the severity of PE(P＜0.05).After adjusting for BMI,there were still statisti-cally significant differences in the levels of threonine,glutamine,and methylhistidine between the PE group and the control group(P＜0.05).The area under the curve of the combined detection of serum threonine,glu-tamine,and methylhistidine for diagnosing PE was 0.734.Conclusion There is a certain correlation between serum levels of threonine,glutamine,and methylhistidine and the severity of PE,and the combined detection has high diagnostic value for patients with PE.