In order to detect the Acoustic Emission(AE) signals in solid materials, a novel ring cavity all fiber F-P interferometer is proposed.By welding the incidence and the exit of a 2×2 optical fiber coupler directly,an optical fiber ring cavity is constructed,which can be attached or embedded in the measured solid to detect the AE signals.The detection property of the optical fiber sensor is determined through the theoretical derivation and the computer simulation.Otherwise,a piezoelectric ceramic(PZT) is powered by signal generator to generate a continuous known AE signal,and a blast wave is adopted to simulate the burst AE signal in marble slabs.Then,they are detected by the optical fiber sensor,and the characteristic frequencies of AE signals are obtained by the Fourier technique.Experimental results indicate that the system can detect AE signals that cause the optical fiber stretching to 10-8 m in an axial direction and can identify the characteristic frequency of AEs.For it can work without the match of optical path and is suitable for monitoring the large scale component,the sensor provides a new method for the health examination and the monitoring of material structures.