Loufanggou vanadium deposit of Shangnan County in Shaanxi is a typical sedimentogenic vanadium deposit, and its ore body occurs in siliceous rocks of Shuigoukou formation in Cambrian system, which occurs as stratified or like-stratified. The host rock mainly consists of carbonaceous or siliceous slate, mudstone, carbonaceous or siliceous slate, and relatively little argillaceous slate. After studying diagenesis and mineralization, the author believes that the formation of vanadium ores is primarily correlated with sedimentation which is involved by hot water. The direct clue for prospecting in field is carbonaceous and siliceous slate, argillaceous slate, and calcareous or argillaceous orbicular concretion contained in them.