The invention relates to an ozone on-line injection, reuse and destruction system, which draws liquid to be mixed with ozone through a pump. The system mainly comprises a gas-liquid separation device and an ozone destruction device. When mixed with the drawn liquid, some of the ozone may dissolve in the liquid and the undissolved portion is recovered and reused, while the ozone, oxygen and nitrogen that cannot be reused are introduced into an ozone destruction device. The ozone destruction device contains an ozone destruction medium so that it can decompose ozone into oxygen that can escape into the environment along with the undissolved oxygen and nitrogen, thereby avoiding environmental pollution caused by the direct release of ozone.