Studies on soil nutrient responses to soil erosion and deposition at watershed scale can provide important scientific basis for soil erosion risk assessment. The Binzhou watershed, a typical thin layer Mollisol region in Northeast China, was selected as the study area. Based on soil sample collection and laboratory analysis, and combined with ¹³⁷Cs tracer method, the soil nutrient contents between erosion-dominant sites and deposition-dominant sites were compared, and the spatial distribution of soil nutrients at watershed scale and their responses to soil erosion and deposition rates were explicated. The results showed that soil erosion-deposition processes obviously affected soil nutrient contents at watershed scale. Comparing with soil deposition-dominant sites, the contents of soil organic carbon (SOC), total nitrogen (TN), NO₃—N and available phosphorus (AP) at the soil erosion-dominant sites were reduced by 27.4%, 21.1%,29.2% and 54.1%, respectively. Meanwhile, the SOC and TN contents between both in soil deposition and erosion sites had extremely significant differences, and the AP contents at both sites had significant difference; while there was no significant difference in NO₃—N contents at the both sites. The contents of SOC, TN and AP had significant negative correlations with soil erosion rates. Moreover, the spatial distributions of SOC and TN contents at the watershed scale were opposite to the spatial distribution of soil erosion rate, which indicated that soil erosion was the key driving factor for soil quality degradation in the study area.