The smoke dust generated on the scene of fire is analyzed and simulated by using an aerosol generator. The standards for the smoke density measuring systems used in smoke detectors are listed. A fire smoke density measuring system based on infrared technology is proposed. The information acquisition unit of the measuring system consists of an infrared transmitting tube and an infrared receive tube. First, the smoke information acquired by the acquisition unit is filtered, amplified and sent to an analog-digital converter for digital processing. Then, the digital signals are sampled and discriminated by a MCU information processing system in real time. Finally, the obtained data are displayed or transmitted to the host computer through a network bus. The system has the features such as simple structure, easy mounting and higher accuracy.