FDS (Fire Dynamics Simulator) is developed by NIST (National Institute of Standards and Technology),a computational fluid dynamics software. In order to verify the accuracy of FDS, we used FDS to establish cable tunnel model, set materials, such as fire sprinkler water parameters,then did the simulation experiments and compared with the experiments of Department of Safety and Environmental Protection Institute of Metallurgy and Castle Peak Power Plant in Hubei Province cooperation experiment " cable-tunnel- fire effective fire extinguishing technology"([1]), analysed experimental data, it is founded that FDS simulation is accurate.