The reuse of fracturing flow-back fluid is of great significance to environmental protection and cost saving of oilfield development. However, the flow-back fluid will turn black and become smelly at high temperature in summer due to bacterial growth, seriously influencing its site application. Based on the research of bacterial species, breeding regularity, the harm of bacterial and the reason for solution hydration in Sichuan and Chongqing areas, sterilization effect of different bactericide was evaluated and three kinds of bactericide were selected to make compound composition experiment. The new bactericide, with its high value of popularization and application, has excellent effect in Sichuan and Chongqing.