Flow back fluid during matrix acidizing in carbonates reservoir has the characteristics of complex composition, variable physical and chemical properties, high content of crude oil and suspended solids. If discharged directly to the ground, it will cause serious environmental pollution and waste resource. A novel and environmentally friendly treatment method to solve this problem has been developed by optimizing surface flow back process, selecting chemicals, modifying filter types and equipment structure. The overall treatment strategy is to separate oil, gas, water and solid phase, inject dehydrated crude oil into pipeline, ignite gas, discharge water after meeting the requirements of industrial wastewater discharge standard, and treat solid phase harmlessly. Some problems such as emulsification, foam fluid and organic scale have been solved by optimizing acid recipe and adopting new chemicals. This novel technique successfully solved the environmental pollution problem and has high economic benefits.