The work aims to obtain a nickel coating of excellent comprehensive performance on fiber bragg grating surface by optimizing electroless plating process. A metal coating was deposited on nonmetal surface based upon displacement reaction. A continuous smooth nickel layer was obtained by changing temperature and pH value of nickel plating bath and optimizing sensitization and activation treatment. The coating morphology was observed with metallographic microscope. Adhesion of the coating and tensile resistance of nickel-plated gratings was tested with high and low temperature alternating test box, and universal mechanical tester, respectively. Compared with the nickel layer deposited in original plating process, the nickel layer deposited in the optimized electroless plating process was continuous and smooth, indicating that the plating bath was stable and clean, and deposition rate of nickel atoms was reasonable. Optimal conditions were to filtrate sensitizing liquid and activating liquid, perfrom ultrasonic cleaning for 30 seconds after sensitization and activation, respectively. The nickel plating bath was at 92 ℃, and pH value was 3.2, continuous smooth coating as well as stable and clean plating solution were acquired. The tested coating was free from cracking and shedding, and tensile strength of the nickel plated fiber grating was more than 5.5 N. However, in the original plating process, plating bath was unstable, the coating was discontinuous or continuous section was not smooth, and some sections even fell off during ultrasonic cleaning. After optimization of sensitization activation treatment, temperature and pH value of nickel plating bath in the electroless plating process, plating bath is clean and stable, deposition rate of nickel atoms is reasonable, the acquired coating is continuous and dense, and thickness is uniform, so that mechanical property is better.