The usually used smoke fire detector, such as point ionic and photoelectric smoke detector, its sensitivity range is larger than that of flame detector or temperature detector. It is suitable for protecting ordinary industrial and civilian buildings. However, if it is possible to detect the fire pre=early , that is to alarm while not seeing the smoke, the fire will be put out before disasters been made, this is the most ideal fire detecting and alarm method. High sensitivity air suction smoke detect fire alarm system (HSSD), can correctly detect the smoke existence and give out alarm signals before the smoke can be seen by eyes. Its smoke detecting correctly detect the smoke existence and give out alarm signals before the smoke can be seen by eyes. Its smoke detecting sensitivity is 500 times higher than that of an ordinary smoke detector. It provides efficient method for pre-early fire detecting.