In this paper, a novel Fiber-Optic Accelerometer was studied. It demonstrates the operational principle and structure design of the three-fiber accelerometer using a GRIN lens. This sensor consists of three fibers, one GRIN lens and a block. In addition, the effects of angular misalignment are calculated based on the analysis of the coupled power. It′s reasonable in theory and easy to fabricate in practice. This sensor is novel and small-scale in physical structure, and it also offers potential precision. Altogether, it is a multi-purpose fiber-optic accelerometer.