The data base of relation between log and geology has been established by ues of various kinds of log data, core sections, geologic analysis and oil test data. Through matching, autofitting and parameter abstraction and study of the lithological and physical properties and oilgasbearing state, the standard of exact evalution of oilgas reservoirs has been established by use of their normal statistical characteristic roots. By applyin g the corresponding standard value absolute deviation as the accuracy and the squa re root of the sum of square standard deviation as the resolution, the weight coefficient of exact evalution of oilgas reservoirs has been established by autoamplitying the accurary and resolution. This paper describ es the process of establishing the standard and weight coefficient, and shows the field processingexample and its application effect by means of exact evalution and comprehensive interpretation of reservoirs of different oilbearing sequences in the Chengda oilfield.