Abstract: In order to understand the transformation and degradation process of NH₄⁺-N in rivers, the influence of biomass, temperature and c(NH₄⁺-N) on the potential nitrification rate were studied quantitatively through potential nitrification rate model of the river sediment. Sediment samples from typical polluted rivers were collected. Three biomass gradients (high, medium, low), 5 c(NH₄⁺-N) gradients (0.13, 0.63, 1.13, 2.13, 4.13 mmol/L) and 4 temperature gradients (15, 20, 30, 40℃) were set, and the potential nitrification rates were determined. The potential nitrification rate model was established, and the effects of biomass, temperature and c(NH₄⁺-N) on nitrification rate were quantitatively analyzed. The results showed that:(1) under the conditions of high, medium and low biomass, the potential nitrification rate ranged from 0.10 to 0.26 μmol/h, from 0.03 to 0.16 μmol/h and from 0.02 to 0.07 μmol/h respectively. (2) The potential nitrification rate of sediment increased exponentially with temperature. However, high temperature shows obvious inhibition effect. The nitrification rate constant k was 5.9, 9.3, 18.1 and 10.6 μmol/(g·h) at 15, 20, 30 and 40℃ respectively, and the temperature correction factor θ was 1.074 at the range of 15 to 30℃. (3) The limiting effect of c(NH₄⁺-N) on nitrification rate conformed to the Monod equation. The half-saturation concentration K_s was 0.02, 0.05 and 0.13 mmol/L under high, medium and low biomass respectively. The research suggested that the potential nitrification rate model can well reflect the influence of biomass, temperature and c(NH₄⁺-N) on the potential nitrification rate of river sediment, and can provide an effective means for quantification of nitrification capacity of sediments.