Abstract: A kind of psychrophile strain named pseudomonas flava WD-3 was isolated from the sediments of Nansihu Lake in winter, and it was used as the microbial carrier. The carbonized rice straw was prepared to be biocarbon as adsorbent, and the biochar-fixed Pseudomonas flava WD-3 bacteria was added into the vertical flow constructed wetland sewage treatment system to discuss the removal efficiency of nitrogen in wastewater of low temperature and to simulate the kinetics of degradation of pollutants in constructed wetland by a simplified Monod Model. The results demonstrate that the removal efficiency of nitrogen in waste water in constructed wetland was increased significantly, when hydraulic retention time was 5 d. The degradation kinetics of TN, NH₄⁺-N, NO₂^--N, NO₃^--N were accorded with the Monod Model by biochar-fixed Pseudomonas flava WD-3.