405 Series flame detectors (short-called the flame detector as follows) provide a new generation of fire detection capability and technical standards. The flame detectors which adopt a specially designed pieces of narrow-band infrared sensors and Blind type solar daylight UV sensors can distinguish the real flame radiation and interference sources effectively and reduce the impact of environmental factors on detector extremely by means of the built-in 16-bit microprocessor and proprietary signal algorithm processing. The detector can set 5 different Sensitivity levels in order to meet more needs in different location. We collected a large number of experimental data through market research and customers’ feedback. We have made a big improvement based on its existing in the hardware circuitry and software algorithms.