The electrochemical behaviors of acetylferrocene at a disk electrode in 0.2mol/L LiClO4 solution had been determined by using cyclic voltammetry. Two methods were used to determine the diffusion coefficient of acetylferrocene, in which the rotating disk electrode was motionless and rotational respectively. Electrochemistry experimental results show that the electrochemical process of acetylferrocene at the rotating disk electrode belongs to reversible redox reaction which was controlled by the diffusion. The peak-peak potential ΔEp and the number of transfer electron n were 56.5 mV and 1 respectively. The diffusion coefficient of AFc and AFc+ were 4.74×10-5 cm2/s and 4.47×10-5 cm2/s determined by the currentvoltage curve in static disk electrode. And the diffusion coefficient of AFc and AFc+ were 5.20×10-5 cm2/s and 5.07×10-5 cm2/s according to the relationship of the peak current and the scan rate in rotating disk electrode, which was little faster than that of in static disk electrode. Rate constants of reduction process and oxidation process were 7.17×10-3 cm2/s and 8.31×10-3 cm2/s, respectively.