Effluent quality of town wastewater treatment plants based on oxidation ditch treatment technology from 2015 to 2017 were analyzed statistically with regard to COD，NH3-N，BOD5，TN，TP and SS The results showed that the standardreaching ratios of six indexes were above 978% and the average removal rates of NH3-N and BOD5 were higher than those of TN and TP Removal efficiencies of NH3-N and BOD5 were more centralized，while those of TN and TP were decentralized Effluent concentration of each index had great dispersion due to different season and the imported concentration，and those of TP and TN were distributed normally 95% confidence interval of exports water quality meets the firstlevel standard of“Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant”(GB 189182002) The effluent concentration of BOD5 and COD depends on the reducing organic pollutants in the outlet water In addition to negative correlation between NH3-N and TP，there is a positive correlation between the other 2 indexes