A pilot scale experiment and a numerical estimation on the performance of ozone/hydrogen peroxide process for the reuse of secondary effluent, were conducted to research the methodology and effects of controlling of dissolved ozone concentration for variation of secondary effluent quality. The major findings obtained are as follows: (1) the amount of TOC and COD removals and the hydrogen peroxide concentration of effluent are stabilized by maintaining dissolved ozone concentration at a fixed level; (2) there exists an optimal dissolved ozone concentration for TOC and COD removals (the range from 0.1 to 0.3mg/L in this study); (3) numerical estimation showed that TOC removal changes by 0.6mg/L with the variation of bicarbonate concentration from 14 to 21mg/L.