［Objective］In order to explore the characteristics and influencing factors of snowmelt erosion on contour-ridge farmland in the black soil region of northeast China，a study was carried out to monitor the snowmelt process on farmlands with the same slope gradient but different slope lengths in the Mahuagou small watershed in Mudanjiang City，Heilongjiang Province. The aim was to explore the patterns and dynamics of such erosion process.［Methods］During the spring snowmelt season，the snowmelt erosion process was investigated on contour-ridge farmlands with three distinct slope lengths（5，20 and 100 m）. The changes in snow depth，runoff rates，sediment concentration，total runoff，and sediment yield were analyzed.［Results］1）Snow depth showed a significant downward trend during the snowmelt period，with a faster decrease in the mid-melt phase，and a relatively slow decrease in the initial and final phases. The complete melting times for slopes of 5，20 and 100 m length were 5，6 and 6 days，respectively. 2）During the snowmelt process，the 100 m slope started to produce runoff around 9：30 every day and stopped around 17：30；the runoff generation times for the 5-m and 20-m slopes were about an hour later，and the runoff generation ended about an hour earlier. The cumulative runoff durations for the 5，20 and 100 m slopes were 5，6 and 7 days，respectively. The runoff rate and sediment concentration both initially increased and then decreased，and both increased with increasing slope length，with the peak sediment concentration lagging behind the peak runoff rate by approximately 0 to 2.0 hours. 3）During the snowmelt process，the daily total runoff and sediment yield followed the order of 100 m slope> 20 m slope > 5 m slope，and they both initially increased and then decreased on all slopes.［Conclusion］During the snowmelt process，the patterns of change in snow depth，runoff，and sediment production exhibit similarities across various slope lengths. As slope length increases，there is a corresponding increase in runoff duration，runoff rate，sediment concentration，total runoff，and sediment yield. Investigating the snowmelt erosion process on contour-ridge sloping farmlands with different slope lengths offers valuable theoretical insights for mitigating soil and water loss on sloping farmland in the black soil region of northeast China.