The soil-rock mixed colluvial slope was selected to study the feature of sediment yield that was affected by four gravel contents(0%，20%，40%，60%) and four discharges(2 L/min ，4 L/min，8 L/min，16 L/min) in indoor artificial runoff experimental condition．The results showed that: the process of sediment yield indicated that the sediment yield overall increased first, and then decreased, reached a steady finally with erosion duration. Sediment volume increased with increasing discharge, whereas sediment concentration decreased with increasing discharge; sediment volume and sediment concentration firstly decreased and then increased with increasing gravel content at the discharges of 2 L/min and 4 L/min, existing critical gravel content (20% - 40%), but sediment yield and sediment concentration increased with increasing gravel content at the discharges of 8 L/min and 16 L/min. According to the relationship between sediment yield rate and sediment concentration, it was indicated that the effect of gravel content on sediment yield existed critical gravel content (20% - 40%). Gravel content and discharge could be used to predict sediment yield rate of soil-gravel mixed colluvial slope correctly, but prediction for sediment concentration was poorer. The effects of discharge were higher than gravel content.