The fire testing actions with 2 kinds of fiber Bragg grating detectors are carried out in a fullscale tunnel testing platform; and then the influence of fire alarm thresholds under wind load on alarm response time and that of wind load on response velocity of fire detector are analyzed. The testing results show that: 1) The alarm time of fire detector is reduced by 24 s under low wind velocity of 0.4 m/s; and the alarm time of fire detector is reduced by 4 s under high wind velocity of 5 m/s when the fire alarm threshold reduces from 10 ℃/min to 3 ℃/min. It is proved that the fiber Bragg grating detector under low wind velocity is more sensitive. 2) The influence of wind velocity on smoke diffusion is significant. The response velocity of the detector at downwind direction is much larger than that at upwind direction, according to which, the diffusing velocity and reaching place of smoke and wind load velocity when fire can be calculated.