Abstract: Based on the two aspects of operation cost and environmental benefits of the sewage treatment plants (STPs), the evaluation index system with four evaluation indexes, i.e. unit construction cost, unit operation cost, COD reduction rate, ammonia nitrogen reduction rate, was constructed. Then the entropy weight method was used to determine the corresponding weight coefficient, and the Euclid approach degree applied to realize the objective evaluation of the comprehensive benefits of the STPs. Based on the treatment quantity and water quality, 47 STPs in Liaohe River Basin were divided into four groups. The results showed that the superiority of A ²/O technology was more obvious when the water quantity was under 20 000 t/d and the effluent water quality was up to Level 1A standard of GB 18918-2002, while in the process that the water quantity was above 20 000 t/d and the effluent water quality was up to Level 1A, MBBR+ UV disinfection technology showed better performance in the comprehensive benefit.When the water quality was under 20 000 t/d and the effluent quality was up to Level 1B standard, the superiority of A ²/O technology was obvious, and in the process that the water quantity was above 20 000 t/d and the effluent water quality was up to Level 1B standard,the advantages of Linpaoer technology and BIOLAK technology were obvious.