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Particulate-associated trace metals have been regarded as an important pollution source for urban surface runoff.Cd,Pb,Cu,Zn and total solids (TS) washed off two different surfaces (low-elevated facade and road surfaces) under two kinds of antecedent environmental conditions (dry and snow-melting) were determined in this study.Wet-vacuuming sweeping (WVS) and surface washing (SW) methods,representing the maximum pollution potential and common rainfall-induced wash-off condition respectively,were used to collect the particulate matters.The result shows that the wash-off concentrations of trace metals were found in the order of Cd (2.28 ± 2.08 μg/l) ＜ Pb (435.85 ± 412.61 μg/l) ＜ Cu (0.93 ± 0.61 mg/l) ＜ Zn (2.52 ± 2.30 mg/l).The snow-melting process had a considerable influence on the wash-off concentrations of the trace metals on both road and facade surfaces.It reduced ＞38％ and ＞79％ of metals and TS concentrations in the facade surface and road surface runoff respectively.The wash-off concentrations of Cd,Cu,and Zn on the road surface 45-780％ higher than those on the facade surfaces.The sensitivity analysis based on the Bayesian network indicates that the wash-off concentrations of metals were mainly dependent on the antecedent environmental conditions or the surface properties while the sampling methods had a minor influence.Therefore,to accurately model the pollutant migration in the surface runoff requires an improving method considering different surfaces and antecedent environment conditions.