Abstract: A new technology for evaluating leakage of concrete structures was established based on ground penetrating radar and microwave moisture detection technique. The condition of the concrete structure was firstly evaluated with ground penetrating radar to find the location of leakage, and then the degree and range of leakage were diagnosed accurately with the microwave moisture detection technique. Combination of the two methods could minimize the limitation of the individual and improve the accuracy. The results of experimental research and engineering application demonstrated that the system had numerous merits in locating and evaluating the degree of leakage in concrete structure. It was accurate, efficient, and comprehensive, meeting the requirements of engineering purpose.