Abstract: The effects of denitrifying bacteria dosage on the bioremediation of sediments were explored． The sediments，as well as water samples，taken from Chaoyang Creek in Nanning with four different dosages of denitrifying bacteria were studied under laboratory conditions． The results showed that the dosage of denitrifying bacteria at 0. 5 g /m3 had better bioremediation effect of sediments than other three dosages after 6 weeks，the sediment thickness decreased 3. 43 cm，removal efficiency of organic matters was 13. 6%，growth rate of G was 280. 8%，the oxide layer was about 0. 7 cm，every indexes achieved stability after 25 days． The dosage of denitrifying bacteria at 0. 25 g /m3 was better than others to improve water quality，the removal rates of COD，NH3－N，TN and TP in overlying water reached 76. 5%，94. 4%，87. 8% and 79. 4% respectively after 6 weeks．