The combined process of "coagulant sedimentation+03+biosand filter+GAC" was a-dopted to treat secondary effluent of wastewater treatment plant,and the impacts of ozone dosage onpollutants removal were investigated.The experiment results showed that the average removal rates and chroma were 70.61%,54.92%,20.63% and 42%,respectivelywhen the ozone dosage varied in a range .When the ozone dosage was 3mg/L,theprocess reached the highest removal rate of and chroma,which were 99.41%,80.13%,28.06% and 58.33%,respectively.It can be seen that combined process of "toagulant sedimentation biosand filter+GAC" has a effectively pollutants removal rate in sec-ondary effluent treatment,and it can improve the water quality comprehensively.The process has abright prospect application in secondary effluent treatment.