A study was carried out on the intensification of a pond system, consisting of an anaerobic pond, a facultative pond and a polishing pond, in Anda City, Heilongjiang Province, by fibrous carriers packed in the anaerobic pond, by means of which the performance of the pond system was remarkably improved with higher removal capacities and efficiencies for SS, BOD5, COD, TN, TP and bacteria, compared with the conventional system. The mechanism for the intensified effect was found to be ascribed to the increase of biomass in the form of biofilm attached to the surface of the fibrous carriers and more even distribution of the biomass in the pond. A mathematical model based on the complete mixed flow pattern was developed both for the intensified and conventional anaerobic pond, and the organic degradation rate constant value K in the former was found to be much greater than that in the latter. The microbial communities in both the ponds were also observed.