The wave-speed prediction method of leaking pipe is proposed according to pipe sound vibration theory and exact situations of the leaking pipes, which is based on cross-correlation and positioning method of leaking pipe sound vi b ration characteristics, and it is proved that the wave-speed prediction method is correct by using leak detection experiments of PVC pipes with cross-correl a tion method. The results of experiments show that the wave-speed prediction met hod makes the cross-correlation techniques more effective and precise, and reduc es the relative error of leaking location under 5 percent.