By distributing influent to different action zones, a high sludge concentration and high sludge concentration gradient were carried out in ECOSUNIDE treatment system. Carbon source was respectively supplied to anaerobic and anoxic tanks, meeting the demand of PAOs for phosphorus release and denirifiers for denitrification. The operation mode of muliple A/O (anoxic/oxic) was employed to avoid the inhibition of nitrate on nitrification and phosphorus accumulation, improving the nutrient removal efficiency without internal reflux. In the paper, the experiments were performed on ECOSUNIDE to investigate the change law of water qualities in the whole system by monitoring MLSS and every index including CODCr, ammonia nitrogen, total nitrogen and total phosphorous, etc. From the results, the removal rates of CODCr, ammonia nitrogen, total nitrogen and total phosphorous were 87.28%, 96.99%, 77.97% and 79.92% reseparately and there was a consistency of the removal rule for every kind of pollutant in the system.