Abstract: Based on various waterbody diffusion model and the strict mathematic deduction,a modeling system(quantitative estimation model) is developed to identify and estimate the harm effect on the accidents in water environment,whose contents include the identification of dangerous source,the est imation of the thick degree line of the characteristic endangered area and endangered period of an accident,and estimation of the endangered period for backward position of the accident,and the like,and the calculation of any concentration isoline's rigor time-space location and specific pot location.As the extended formulate of the various waterbody diffusion model,it has the same conditions,and is easy to use with exact results.It can be applied broadly to the dangerous engineering design and engineering insurance,the environmental risk assessment and management,the environmental impact assessment,the environmental planning,etc.