In order to solve the problems of easy damage and low sensing sensitivity of fiber grating, a micro spot welding machine and prestressed platform are designed and customized. Firstly, the optical fiber is nickel plated and metallized, then the optical fiber is encapsulated in capillary steel pipe by capillary resistance spot welding, and the temperature sensing characteristics are detected. The test results show that the surface of the electroplated nickel layer is bright and smooth, and the optical fiber is closely combined with the electroplated nickel layer. The fitting linearity between the central wavelength and the temperature change of the optical fiber sensor is very good, which can reach more than 0.999, and its temperature sensitivity is about 2.8 times compared with the bare grating sensor.