By performing experiments on the side channel solid-liquid separator in integrated oxidation ditch at Shishui,Shandong Province,the effect of solid-liquid separation and sludge recycle is examed.Additionally,according to the mechanism of sludge recycle,the modified measure with bump was provided to improve the effect of soli-liquid separation.All studied can serve as references to making better use of solid-liquid separator in wastewater treatment project.