Abstract: In order to investigate the characteristics of cable fire and analyze the fire suppression effect of powder extinguishing system and high- pressure water mist system, a series of fullscale experiments and numerical simulations were conducted in the cable compartment of a practical utility tunnel project. A ethanol fire with HRR=0.7 MW was set under the bottom cable rack. The corresponding development of fire and the spread of smoke were observed to analyze the characteristics of cable fire in the cable compartment. By comparing the changes in temperature and smoke under two common-used fire suppression systems, the suppression effect of powder and high-pressure water mist systems were analyzed. Based on the full- scale experiments, the simulation software FDS was adopted to supplement and verify the results. Results indicate that after closing fire door of cable cabin, cable fire could not keep spreading, and the temperature stabilized between 600 ℃ and 700 ℃ . The powder extinguishing system had a quite short effective extinguishing time and a limited cooling effect. When the temperature above the fire source dropped to about 440 ℃ , cables began to reignite. By contrast, the water mist system could suppress fire for a consecutive and longer time and had a markedly positive influence on reducing temperature and suppressing the spread of smoke. Therefore, the water mist system could bring beneficial conditions for firefighters to enter the compartment and rescue.