Objective To perform nickel coating on the surface of carbon fiber using chemical deposition under ultrasonic condition so as to study nickel plating for surface modification of carbon fiber. Methods The organizational structure, microstructure and plating rate were changed by the pH value of plating bath and temperature of heat treatment as well as ultrasound, which were investigated through XRD and SEM analysis. Results When the pH value was between 8. 0 and 10. 0, the deposition rate was increased with the pH value, the coating was uniform, dense and well bonded with the matrix and the coating thickness was about 0. 5 μm. The carbon fiber had a reunion phenomenon, when the pH value was between 10. 0 ~ 11. 0. The plating layer was recrystallized to generate Ni3 P phase after being kept for 10 min at the heat treatment temperature of 400 ℃ . With increasing of the temperature, the plating layer crazed and the gap between the crazed parts decreased. Conclusion The pH value had great influence on deposition and would lead to carbon fiber reunion when exceeding the limit value. Too high temperature for heat treatment would lead to recrystallization and crack of the plating layer.