Using the experimental carbonsand filter system to make the PAC and PALL mixedsludge circumfluence to flocculation pool,the removal effect of organic matter and ammonia nitrogenwas investigated,the optimal reflux ratio are obtained.The results show that when the system is insteady running,coal mud reflow process on turbidity,organic matters and ammonia nitrogen removalefficiency are better than carbon mud reflux process;within a certain range(3%)or less,the remov-al rate increases with the increase of reflux ratio increases;when the reflux ratio is 5%,because ofthe microflocs and excess backflow sludge,the effect of sedimentation tank and filter burden is tooaffecting the removal efficiency of each index.