Taking supply water source of Xi'an city as an example, by the help of Matlab software, using fill and yield model, the Inverse-Gauss flow concentration model, runoff-sediment relation model and Viney model, the transfer and transform processes of phosphorus from 1981 to 1990 were modeled continuously. Phosphorus pollution loads of Heihe River were also estimated. The result shows that the continuous modeling result accorded with the generic law of phosphorus loss. The relative error between modeling result and monitor interpolation result was not more than +/-30%. So the modeling method proposed in this paper could be used to model continuously the transfer and transform processes of phosphorus in Heihe river watershed. This study was only primary attempt to non-point source pollution continous model, therefore, the modeling method needed to be improved and perfected further.