Non-point source pollution is the main origin of water pollution in the Taihu Lake basin.Quantitative study of non-point source pollution load can provide decision supports to its forecast

prevention and treatment.In traditional study

GIS and non-point source pollution models were integrated in the loose coupling way that has the defects of a large amount of data management and transform works.An estimating system for non-point source pollution load in the Taihu Lake basin was designed and developed using mosaic integration.Structure of the system and its functions were introduced and the realizing flows of three main function modules were discussed

including modules of SCS

USLE and non-point source pollution load models.Using the system

non-point source pollution load of total N in Wuxi City in 2005was estimated to be 8 014.43t

which originated mainly from agricultural production and waste water drainage of daily life.Application of the system showed its practicality because the calculating procedures of non-point source pollution models were simplified and the result reflected non-point source pollution situation and its relationship with land use in the study area objectively.