As far as super-highly watered cut oil fields are concerned, the appreciation of the reservoirs should be conducted quantitatively so that the results can govern the dependable crop and the potential capacity. Nowadays, there are some waysof evaluating the reservoirs, such as mathematical statistics, comprehensive mathematical discrimination, professional weight discrimination. The bounders of different kinds of reservoirs are not defined scientifically in these methods. Instudying the character of V oil group reservoirs in Henan, China, we took the way of professional weight discrimination to evaluate the core wells, getting thedata of comprehensive apprehension. The reservoirs are divided into 4 types by using cumulative probability to determine the bounders of the reservoirs. The principle of using cumulative probability to determine the bounders is that the comprehensive parameters of evaluation will drop on the same line as long as the reservoirs have the same characters. Using the step by step discriminant program to define the non-core reservoirs, therefore, creating the discriminant equations of evaluating the reservoirs. The field experiment shows that the data agreement percentage is over 90%, showing that the new method is feasible. 