In order to study the erosion caused by spring snowmelt of slope farmland in Northeast China and the affecting factors, in-situ observation was carried out on a sloping farmland in small watershed in Jixing, Jilin province. The changes of runoff and sediment yield during snowmelt were analyzed, the effects of factors such as snowmelt runoff and soil thawing depth on snowmelt erosion were investigated, and process and change rules snowmelt erosion of sloping farmland were explored. The results showed that, under the meteorological conditions of the average temperature of 0 to 3.8 ℃, spring snowmelt erosion was relatively concentrated, runoff and sediment yield increased first and then decreased. Snowmelt runoff and soil thawing depth were important factors affecting snowmelt erosion. In the early stage, runoff from melting snow increased dramatically, and accounted for 59.15% of the total snow melting period, soil was frozen at the same time. In the middle stage, snowmelt tended to stabilize, surface soil began to thaw, runoff decreased and sediment yield continued to increase, the amount of erosion reached the maximum and accounted for 41.74% of the total erosion. At the end, there was no snow on the slope, and the depth of soil thawing increased, runoff decreased and sediment concentration reached the maximum (8.00 kg/m3). Spring snowmelt erosion of sloping farmland was affected by the topographic changes of ridge area and catchment basin, runoff and sediment yield showed a strong regularity. When their peak frequency was consistent, runoff sediment showed an “8”cycle lag relation, but showed a compound cycle lag relationship when their peak frequency was inconsistent.