The loss of soil and water in sloping farmlands has become a significant focus in soil and water conservation. This study examines the impact of varying concentrations of seaweed polysaccharide-based materials (SA-01) on runoff characteristics and sediment production in sloping farmland, using simulated rainfall experiments. Furthermore, the intrinsic mechanism of SA-01 in regulating soil erosion on slopes is elucidated through an analysis of soil disintegration rates and permeability coefficients. Results showed: (1) Soil disintegration rate decreased by 66.1% to 92.8% with the application of different concentrations of SA-01 compared to the control group. (2) The effect of slope on runoff generation did not exhibit significant differences. However, the runoff rate on the slope with a 1.00% concentration of SA-01 was twice that of the control group, and the runoff rate on the slope with concentrations ranging from 0.50% to 1.00% exceeded that of the control group. (3) The stable sediment yield rate after the application of SA-01 ranged from 0.38 to 0.67 times that of the control group. As the application concentration increased, there was a notable decrease in cumulative sediment production, leading to sediment reduction benefits amounting to 72.21% to 94.84%. The findings suggest that seaweed polysaccharide-based materials have substantial impacts on the regulation of farmland erosion. These results can establish a theoretical basis for future research on novel materials for preventing and controlling soil erosion in sloping farmland.