To explore the ammonia nitrogen treatment capacity and nutrient composition of sinking flocs and floating flocs with and without carbon source. Under the two conditions, three treatment groups were set up respectively-sinking flocs, mixed flocs, and floating flocs. Each group of TSS (Total Suspended solid, TSS)was about 150 mg/L and alkalinity was about 300.00 mg/L, 10 mg/L NH4Cl was used as the nitrogen source and glucose with DOC/TN=15 was used as the carbon source. A 3-day continuous water quality monitoring test was carried out. At end of the test, flocs were taken to measure the nutritional indicators. The results showed that the total ammonia nitrogen removal rate of sinking flocs, mixed flocs, and floating flocs with carbon sources were (1.03±0.03) mg/g·h and (1.00±0.01) mg /g·h, (1.05±0.07)mg/g·h; the removal rate of ammonia nitrogen for sinking flocs, mixed flocs and floating flocs without carbon source were (1.20±0.16) mg/g·h, (1.28±0.03)mg/g·h, (1.02±0.03)mg/g·h, ammonia nitrogen removal rate for sinking flocs and mixed flocs without carbon source was higher than the sinking flocs and mixed flocs with carbon source and the difference in the ammonia nitrogen removal rate of the floating flocs between the two groups are not significant. The nitrite nitrogen (NO2--N) of the floating flocs has a higher peak concentration, which is (1.85±0.05) mg/L under the condition of adding carbon source and (3.32±0.38) mg/L which are under the condition of not adding carbon source, the final concentration of nitrate, total nitrogen and dissolved total nitrogen of sinking flocs, mixed flocs and floating flocs in the groups which are with carbon source and without carbon source were significantly different (P<0.05). With the addition of a carbon source, the floating flocs have more content of Eicosapntemacnioc Acid (EPA) and fatty acids. Without the addition of a carbon source, the sinking flocs have more content of amino acids and floating flocs had a higher content of EPA. The results showed that the sinking flocs have a better capacity for removing TAN and NO2—N, the floating flocs had a higher nutritional value.