Aiming at the deficiency of irrigation areas evaluation methods, the improved matter-element extension assessment method is introduced in this paper. The comprehensive weight determined method based on game theory integrates the subjective weight with objective weight, solving some problems occurred in traditional extension assessment method like index weight only depends on index data, ignoring the value attribute of index. In grade assessment, the deviation degree is gained through calculating the variable characteristic value. The running conditions of Donggang irrigation areas in 1997 and that of in 2004 are evaluated in this paper via the method of improved matter-element extension assessment, and the evaluation result of Donggang irrigation areas fits the actual condition finely. Through case evaluation, the method is proved reasonable and feasible in application to running condition evaluation of irrigation areas.