An experiment was conducted to study the dynamics and budget of nitrogen and phosphorus in two crucian carp（Carassiusauratus var.pengzenensis) pondsfor about three months.The results showed that the concentrations of different forms of nitrogen and phosphorus in the water column were increased significantly during the late experimental period.The concentrations of total nitrogen and phosphorus were increased by 7.8 times and 4.4 times in pond A,and by 3.6 times and 2.4 times in pond B,respectively.The concentration of total nitrogen and phosphorus in pond mud had no significant changes.Feed is the major source of nitrogen and phosphorus in the pond,accounting for 88% and 96% of the input of nitrogen and phosphorus on average,respectively.The accumulation of nitrogen and phosphorus in fish body accounted for 29.73% and 10.06% of the total expenditure in pond A,31.29% and 9.03% in pond B,respectively.Most of the nitrogen (53%) and phosphorus(87%) were deposited in the mud or left the water body through leakage,denitrification and ammonia volatilization.