The typical functions of the optical fiber are communication and sensing. However, the fiber functions need to extend to meet the requirements of the development of artificial intelligence. This paper achieves an all-fiber device with storage and logic computing functions using a single-mode fiber and Ge2Sb2Te5 (GST) material. We use the pulse amplitude modulation (the switching energy is about 50 nJ) to switch the GST state for performing the eight-level data storage (3-bit). The all-fiber memory device has the advantages of high optical contrast (about 38%), good reversibility, and high repeatability. We implement the all-optical logic operations (“AND” and “OR”) by using two memory cells in series and parallel. For the first time, we use the single-mode optical fiber to realize storage and computing functions, and this intelligent fiber has tremendous application potential in intelligent optical fiber communication and portends a new paradigm for brain-like computing.