Objective To explore the levels and the clinical significance of serum soluble Endoglin (sEng) and soluble Fms-like tyrosine kinase (sFlt-1) in patients with preeclampsia (PE). Methods Ninety-six patients with PE were included from June 2009 to June 2014. The patients were divided into mild PE group (n=54) and severe PE group (n=42), while 40 healthy pregnant women were in the control group. The general situation and laboratory testing were recorded and the serum levels of sEng and sFlt-1 were detected. All patients were routinely followed up with the recording of delivery and neonatal situation. Results The sEng and sFlt-1 levels were highest in the severe PE group [(7345.02±772.73) and (866.08±203.24) ng/L], which was followed by mild PE [(5 547.08±564.06) and (603.99±138.37) ng/L] and control group [(1 840.93±300.71) and (252.68±83.03) ng/L] (P<0.01). Levels of sEng were significantly correlated with sFlt-1 in both mild and severe PE groups. There were significantly correlations between sEng and sFlt-1 in mild or severe PE group respectively. The level of sEng and sFlt-1 was considerably positively correlated with mean arterial pressure, 24-hour urinary protein, serum creatinine, fibrinogen, umbilical artery shrink/diastole and resistance index value, but negatively correlated with prothrombin time, birth weight and the placenta weight (P<0.05). PE patients with sEng of <5 000 ng/L and sFlt-1 levels of <700 ng/L had the risk of severe complications of 6.8% and 14.0%; while patients with sEng of ≥5 000 ng/L and sFlt-1 of ≥700 ng/L had the ratio fo 40.4% and 37.0% respectively (P<0.01). Conclusion Serum levels of sEng and sFlt-1 in PE patients indicate that the severity of disease and outcomes of pregnancy.