Reduced-scale experimental study was carried out on the heat flow behavior which flows under the sloped ceiling in underground fire. Temperature and flow velocity were measured to characterize the ceiling jet along the sloped stairway ceiling. The methanol fuel was used as a model fire source giving 2.2 and 3.4 kW, with changing the slope angle of stairway adopting of 15, 25, 35, and 45 deg. Based on the experimental data, excess temperature and velocity along the sloped stairway ceiling were examined which are usefully applicable to estimate the activating conditions of heat detector and sprinkler head mounted on the sloped ceiling. Excess temperature in upper exit of the sloped stairway was also examined to analyze the soffit which delays the smoke diffusion. The result shows that the activating conditions of heat detector and sprinkler in the sloped stairway ceiling have to be considered differently in a point of about 30 deg.