At present，Activated sludge model has great value and call be used to improvethe study，design and optimum operation ofwastewater treatment around the world．It has been applied widely in the world． In this thesis，the application and calibration of Activated Sludge Model No．I inthe practical wastewater treatment plant had been implemented．The characterization and parameter of the outfluent from the rotational flow grit chamber had been measured in the WWTp.The actual operation procedure is simulated in case of both steady and dynamic status using simulation software named as WEST，which is from DHi.Where after different simulation analysis is done to analyses the problems existin this factory，and hence based on the analysis result，the optimized suggestion is arised． The result shows that the method of characterization and parameter in this paper Call is practicaL.The heterotrophic yield coefficient YH，Heterotrophic nlax specificgrowth rateμ<,max>，heterotrophie decay rate bH，readily biodegradable substrate Ss and slowly biodegradable substrate Xs could be characterized by the method of batchOUR respirometric experiments which is simple to calculate，and especially theoutcome date is stable． The WEST software was used to simulate the real operation of the WWTP，theresult shows that using the combination of test mensuration and model calibration，good simulation results were achieved though changing ofthe model parameters． The activated sludge model which was promoted by the IAWQ Can be used as auseful tool in operation management，technical improvement and scientific research inWWTPs．Nevertheless WEST software which was based on the activated sludgemodel could simulate the performance of activated sludge process and providevaluable advices for directing WWTPs．