To investigate the levels of high mobility group protein box-1 (HMGB1)and asymmetric dimethylarginine (ADMA)of pregnant women with preeclampsia and their correlation with the wall thickness and lumen area of the placental spiral artery of the women. Methods: The clinical data of 72 pregnant women with preeclampsia from January 2019 to June 2021 were selected in this study. These women were divided into 37 cases with severe preeclampsia in group A and 35 cases with mild preeclampsia in group B according to the severity of preeclampsia. 35 normal healthy pregnant women during the same period were selected in group C. Enzyme-linked immunosorbent assay (ELISA)was used to detect the expression levels of serum HMGB1 and ADMA of the women in the three groups. Electron microscopy was used to observe and measure the wall thickness and lumen area of the placental spiral artery of the women in the three groups. The correlation between the levels of HMGB1 and ADMA of the women with preeclampsia and the wall thickness and lumen area of their placental spiral artery was analyzed. Results: The expression levels of serum HMGB1 and HMGB1 of the women in group A (24.58±4.36ng/ml and 5.03±3.24umol/ml), in group B (17.41±7.41ng/ml and 2.74±0.40umol/ml), and in group C (10.24±2.53ng/ml and 1.87±3.02)umol/ml)had decreased gradually. The wall thickness and lumen area of placental spiral artery of the women in group A (118.14±9.03um and 138.47±28.41um2)had significantly different from those (107.21±8.40um and 156.21±26.74um2)of the women in group B, and those (102.08±8.57um and 190.53±26.59um2)of the women in group C (all P＜0.05). The levels of serum HMGB1 and ADMA of the pregnant women with preeclampsia were negatively correlated with their placental spiral artery wall thickness (r=-0.631, -0.655, P＜0.001), and were positively correlated with their placental spiral artery lumen area (r=0.715, 0.693, P＜0.001). Conclusion: The expression levels of HMGB1 and ADMA of the women can be used as the indicators to evaluate the severity of their preeclampsia, both of which maybe involve in the recast process of placental spiral artery obstacle of the women, and provide certain theoretical support for the pathogenesis of preeclampsia.