The invention provides a manufacturing device of an optical fiber F-P cavity sensor and a manufacturing method thereof. The manufacturing device comprises a bracket, a stepping motor, large and small synchronous belt wheels, a three-jaw chuck, a tapered roller bearing, a vacuum pump, an oxyhydrogen flame hot melting machine, and a capillary glass tube clamp. One end of a capillary glass tube is welded by oxyhydrogen flame, the other end of the capillary glass tube is inserted into a fiber, and the capillary glass tube is inserted into the capillary glass tube clamp. A tail fiber passes through a tube shaft and is fixed and sealed by a rubber washer and a fixing nut. The rotating speed is in a range of 120r / min to 140r / min. The heating of the capillary glass tube is uniform. The vacuum pump is connected with a tower joint and the capillary glass tube is pumped into vacuum while the clamp is rotated. At the same time, the capillary glass tube is heated and melted by the oxyhydrogen flame hot melting machine, and under the effect of pumping, a capillary glass tube wall is collapsed inward to melt the fiber with the capillary glass tube. According to the melting method, the capillary glass tube and the fiber are firmly melted, the sealing performance is good, the penetration of oil and moisture from a welding point to damage an F-P cavity can be effectively prevented, and a solid foundation is laid for the long-term application of the optical fiber F-P cavity sensor in a harsh environment.