A novel optical fiber acoustic emission sensor based on extrinsic Fabry-Perot cavity is proposed in this study. Digital optical processing 3D printing technology is used to create an acoustic vibration-sensitive diaphragm, and the structure is based on flexible digital model design and can be formed in one time. It is easy to integrate with the surface of a standard optical fiber ceramic insert. The experimental results show that the fabricated Fabry-Perot sensor exhibits a high extinction ratio. The acoustic emission sensor exhibits a high sensitivity in a frequency range of 600 Hz--2.4 kHz, and the pressure sensitivity is 2.81 mV/Pa at a frequency of 1.6 kHz. The proposed optical fiber acoustic emission sensor based on 3D printing technology is extremely stable and easy to be fabricated, and it has potential in the fields of acoustic emission detection.