Weighing order method is a kind of efficient method of multi objective evaluation and decision for groundwater quality. Based on three-mark improved hierarchy analysis,the method could reduce the subjectivity of constructing judge matrix through traditional hierarchy analysis method. Through application of mathematical transformation and making consistency of judgment matrix, which can ensure the accuracy and consistency of judgment matrix The paper gave the calculation method of determining weighted index.Through verification of practical example,it compared the result with that of traditional hierarchy analysis method.The result indicated that the operation of the method of improved three-mark weighing determination is simple and in accordance with practice. The method can effectively reduce subjectivity and blindness when determining weight. The calculation of weighted priority order method is simple and can give reasonable category of water quality for groundwater sample and is worthy of popularization and application.