The invention discloses a calibration device of a fiber-optic gyroscope inclinometer, relates to the technical field of fiber-optic gyroscope inclinometers, and aims to solve the problem of coaxiality during fixing. The device specifically comprises a base, wherein the top of the base is connected with a clamping assembly through a rotating assembly, the clamping assembly comprises a main body and a clamping ring, four sliding grooves in a 90-degree circular array are formed in the inner wall of the main body, clamping jaws are slidably connected to the inner walls of the sliding grooves, arc-shaped pads are fixed to the outer walls of the clamping jaws through bolts, the clamping ring is rotationally connected with the main body, a limiting sliding column penetrating through the main body is fixed to the outer wall of the other side of the clamping jaw through a bolt, an arc-shaped groove matched with the limiting sliding column is formed in the inner wall of the clamping ring, teeth are arranged on the inner wall of the clamping ring and engaged with a planet wheel, and the planet wheel is fixedly connected with a worm wheel through a transmission shaft. According to the invention, the contact ratio of the axis of the clamped fiber-optic gyroscope inclinometer and the axis of the main body is relatively high, so that the accuracy of subsequent calibration is ensured.