AbstractAccording to the test and statistical data of Yellow River basin, the environment system is classified in the climate resources subsystem, the water resources subsystem, the land resources subsystem and the social economy subsystem based on the present situation and characters of the basin. In order to evaluate ecological environment quality of Yellow River basin in the year of 2000 and 2004, the index system of the ecological quality evaluation is established and the appropriate evaluation unit and factors are selected. The weight value of every evaluation index is determined by the analytic hierarchy process and the ecological quality is evaluated by comprehensive index method. The evaluation results show that during 2000 to 2004, the ecological environment index rose the fastest in Inner Mongolia, and the slowest in Shanxi. On the whole, the ecological environment index in every province of the Yellow River basin appeared rising. In this basin, the quality of the ecological environment got improved.