In order to analyze the urban wastewater treatment efficiency in northeast China more effectively,this paper uses correlation analysis to determine the efficiency of various relevant factors,combined with second-order quadratic approximation of the investment and operation cost function to fit the actual data,based on which the efficiency of wastewater treatment is analyzed with corresponding indexes.The result shows that the analysis of urban wastewater treatment efficiency in northeast China should be concentrated on designed capacity,actual processing capacity,effluent COD concentration and sludge treatment volume.All the indices above have a positive relation with investment and operation cost,and the margin cost shows a decreasing trend,which means that the efficiency of urban wastewater treatment in northeast China is improved with increasing cost.