Abstract: Using and reforming existing cavern of salt chemical enterprise is an effective method to speed up the construction of gas storage. Lots of caverns formed in the long-term production of salt chemical enterprises in China. Accurately evaluate the tightness of salt caverns is an important issue in the process of existing caverns transformation. The brine injection test uses pump trucks and pipelines to inject saturated brine into the cavern. By monitoring the injection pressure and brine flow, the cavern leakage is calculated to evaluate the tightness of the salt cavern. This method does not need down-hole instruments and equipment and has the advantages of simple operation, low requirements for well conditions and low testing cost. The results of field application show that this method can effectively judge whether the salt cavern has obvious leakage or not, which is a feasible method for the early tightness evaluation of the cavern.