The invention discloses a vibration sensor of a three-component fiber grating. The vibration sensor of the three-component fiber grating comprises a base, an outer shell, a fiber grating, an oscillator, an oscillator clamping seat, springs, and the like. Three same vibration sensors are mutually perpendicularly fixed on the base of a sensor. The outer shell of the sensor comprises two parts, the body part of the outer shell of the sensor is a box structure, five surfaces of the box structure are closed, an opening is arranged on one surface of the box structure, and the other part of the outer shell of the sensor is a sliding cover which covers the opening of the box structure. A circular hole is arranged at the top end of the outer shell, and transmission optical fibers and a sleeve pipe penetrate through the circular hole. A stainless steel cylinder is arranged inside the outer shell, the fiber grating which is coated with elastic materials is arranged inside the stainless steel cylinder, the lower end of the fiber grating is connected with the oscillator, the oscillator is arranged inside the oscillator clamping seat, and the lower end of the oscillator is connected with the bottom end of the outer shell of the sensor through a second spring. A grating is not required to be pasted on a mechanical structure so that restriction on natural frequency of the mechanical structure is effectively avoided and range of measuring frequency of the sensor is largely broadened. The vibration sensor of the three-component fiber grating is capable of measuring vibration amplitude, frequency and accelerated speed which are mutually perpendicular in three directions in real time, and preventing effectively over range damage of the sensor.