The calculating method of the surface water resources of Fuyang River karst mountainous area is to be explored in the paper through analyzing its runoff yield characters.In the course of water resources assessment,the scope of the underground catchment basin should be firstly delimited and the surface catchment area of each river is to be divided based on the hydrogeological materials in this scope.The base discharge of the underground catchment basin and the total surface run-off of every river can be worked out respectively.Then the total amount of the two kinds of discharge is the amount of surface water resources of this area.