Abstract: Annealing can improve the microstructure of the material,increase its toughness,and release its internal stress.The hafnium-doped diamond-like carbon(Hf-DLC)films were prepared by the dual-target co-sputtering technology,and they were annealed at different temperatures.The morphology,bonding structure,hardness,and friction properties of the films before and after annealing were studied.The results show that Hf and C in the Hf-DLC films formed nano-crystalized HfC.The Hf-DLC films are stable at an annealing temperature of 250℃.After annealing at 300℃,the structure of the films begins to change,and the surface particles increase and become rough;when the annealing temperature is above 350℃,the crystallinity of the films is better,and the HfC structure in the films increases.The hardness of the films first decreases and then increases with the annealing temperature,and the film-substrate bonding is improved.This is because the structure of the film changes with the annealing temperature.