Pugou bauxite is a small-sized ore deposit, in which boehmite was discovered for the first time. With the help of polarizing microscope, XRD, 1R and SEM, the author has made a detailed study on the mineralogical properties of boeh mite. Boehmite, γ-A100H, belongs to orthorhombic system. α=β=γ=90º，a0=3.690A， bo=12.162A，co=2. 866A.The crystals are mainly blades and rhombohedral in shape, colorless or yellowish in color,and 0.5μ to 4μ in size. The XRD analyses demonstrate that the charaos}eistic lines of boehmite are d020=1.848, d22o=1.769 and do8o=1.529, The IR analyses show that the characteristic frequency bands are 3300cm-l， 3078em-1, 793cin-1and 364cm-1. Based on indoor studies and field investigation, the author puts forward a preliminary opinion concerning the origin of boeh mite. It is considered that boehmite was formed mainly in two ways during the supergene process: mainly through the direct crystallization of the Si-Al gel and secondarily from the desi- lication of kaolinite.