Fiber Bragg grating (FBG) based force sensing technology receives much attention from various research communities in robotics. In this paper, we investigate a three-axis FBG force sensor for robot finger. A special separated elastic structure with six FBGs attached has been designed for three-axis force sensing. Strain distribution and dynamic performance of the proposed structure are simulated by using finite element analysis (FEA). Six FBGs with different wavelengths were arrayed along a single fiber and divided into three groups to measure Fx, Fy, and Fz, respectively. The experimental results demonstrate that the sensor possesses good linearity, weak coupling, and creep resistance.