The pollutant emission right trade is an economic means based on market, and many developed countries have implemented practices, such as the U.S.A, Germany, Australia, England, ect. Water pollutant emission trading ratio is a pivotally academic technology. On the basis of summarizing the researches on water pollutant emission right trade, the paper emphasizes studying a drainage basin as a research object, establishes the integrated technology framework of water pollutant emissions trade, clears up the definition of water pollutant emissions trading ratio, brings forward the calculation method of water pollutant emissions trading ratio in the drainage basin, and conforms the formulation of water pollutant emissions trading ratio in the drainage basin. The method has been applied in an illustration research on Tai Lake basin.