Pollution receiving capacity calculation for local medium- and small-sized streams short of runoff data can be made with conventional methods. However, it is rather loaded down with trivial details. Based on characteristics of local medium- and small-sized streams and hydrology principle, calculation model of design discharge was set up, which was coupled with the improved water quality model, thereby a simple coupling model of pollution receiving capacity was obtained. By analyzing and verifying, calculation error of the coupling model is not more than calculation error of design discharge. The model could be used in the calculation of pollution receiving capacity for local medium- and small-sized streams short of runoff data.