Abstract: Based on the parameters of horizontal wells which have been put into production, using the method of Grey Interconnect Analysis, we sort out the parameters which have great effect on horizontal wells' recovered reserves according to its importance. Based on the selected main parameters, those wells in the same type of reservoirs can be classified into several groups using the method of fuzzy clustering. Then the new designed well is sorted into one of those groups according to its character. The new well can be evaluated by the production index of the wells in the same group. And the software is also made. This study provides anew filtration and evaluation method for horizontal wells' designing.