〔Abstract〕 Objective To explore the relationship between serum biomarker's concentrations and early complications after single umbilical cord blood transplantation(UCBT). Methods Concentrations of soluble suppressor of tumorigenicity 2(sST2), regenerating islet-derived protein 3-alpha(REG3α), interleukin(IL)-6, IL-8 and tumor necrosis factor receptor 1(TNFR1) in patients with hematological diseases were dynamically monitored on days 0,7,14,21,28 after UCBT(D0, D7, D14, D21, D28) to analyze the relationship between pre-engraftment syndrome(PES), acute graft versus host disease(aGvHD) and infection and the concentrations of five biomarkers. Results There were no significant differences in biomarker concentrations between PES-/PES+ patients at each time point. D28 sST2 was significantly higher in the aGvHD+ group compared with the aGvHD-group(Z=2.236,P=0.036). There was no statistically significant difference in serum biomarker levels between the two groups at each time point according to whether infection occurred before D28. sST2 showed a moderate or high positive correlation with TNFR1 on D21 and D28(rs=0.633,rs=0.821;P=0.005,P=0.023). Conclusion The elevated serum concentration of sST2 on D28 after single UCBT is closely related to the development of aGvHD.