Abstract: Watershed raster river network extraction is an important application of digital terrain analysis applications.A parallel algorithm based on multiple flow direction is put forward in order to reduce pseudo channels and parallel channels which are produced by DEM pretreatment.It simulates the overland flow and uses a more elaborate water transfer model that is inspired by the natural behavior of water on unprocessed DEM. The main advantages of parallel MFD algorithm are put forward on two fronts: the space form of river networks and the efficiency of the algorithm.The experimental results show that the river network of MFD algorithms more aligned with the actual landform tallies.The efficiency of the parallel algorithm is superior of the serial algorithm,R&N algorithm or D8 algorithm.