Abstract: Jacketed structures inner-pipe leakage is difficult to discover the leakage due to the structure of the cover. In this paper, the acoustic emission testing technology is used in the jacketed structure inner-pipe leakage detection because of its real-time performance and high sensitivity, etc. A new acoustic emission parameter was constructed and used for assessment of jacketed pipe leakage in order to improve the evaluation accuracy. By comparing the traditional acoustic emission evaluation effect parameters with the new parameter through the inner-pipe leakage simulation experiment, it was shown that the new parameter evaluation results were more accurate. Cross-correlation positioning method is applied to simulated leak positioning of jacketed structure, position error is less than 10%. The results show that the new parameters can accurately evaluate the leakage intensity, and the cross-correlation positioning method can locate the inner-pipe leakage.