The engineering suitability of typical linear heat detectors for early fire detection in cable tunnels was explored. In cable tunnel environments, an experimental platform was established based on exiting linear temperature fire detectors, including temperature sensing cables, fiber Raman detectors and fiber grating detectors, then two different fire experimental scenes were set up, and the temperature variation and fire detector response time were recorded in the processing of fire simulation. The experiments show that only directly contacting heat detectors can give an alarm response and other non-contact detectors are unable to respond the small-scale fire because a small amount of thermal radiation has no flame for the beginning of the fire. Furthermore, for massive fire, the alarm response time of both fiber Raman sensing heat fire detector and fiber grating sensing fire detector is about 30 s, the temperature over the fire recorded by a thermocouple is less than 35 ℃ in 60 s, while the temperature rising is more than 5 ℃/min within the range of ±3 m. According to the technical characteristics of the three detectors, the engineering suitability of the typical linear heat detectors in cable tunnels early fire detection is analyzed, which can provide technical support for establishing the design specifications of fire alarm.