Abstract: Flow-reaction in double media is widespread in the design of oil field development. It is urgent to solve the calculation problem of acid treatment design in fractured carbonate reservoir. The reaction of acid flowing in fractured carbonate formation is the acidrock reaction under unsteady state filtration in double media. This paper first develops a permeation model of acid flowing in double media, then based on the theory for surface reaction kinetics, the convection-conduction partial difference equation far reaction of acid flowing under steady state is established, which takes both common ion effect and temperature iota consideration. A temperature field model is also built up, and their solutions are given simultaneously by using the steady state-successive replacement method. Therefore, velocity field, temperature distribution and acid concentration distribution are obtained. The method can also be used for calculating the front position of alkaline displacement and the concentration distribution of alkaline water. The flow-reaction in fractured reservoir, a widespead problem, can be resolved by means of the theory and the way provided by this paper. The method has been used for designing the acid treatment加a fractured reservoir in our country.