Introduceding the Measuring principle and working System of a-self-developed dust content Detection System. which is used in detected the particles content of suspended material and smoke in the air, and reflection dust content change in real-time. introduced based on principle of light scattering, The instrument includes an optical sensor, electric circuit, gas channel and center control unit. The instrument also adds device simulation environment that can simulate all kinds of dust content content environment. Instruments selected to receive the signal right angle light scattering optical sensor, by photoelectric conversion and circuit processing, dust particles in the environment available to content and change information. Instruments selected to receive the signal right angle light scattering optical sensor, through photoelectric conversion and circuit processing, available to know the content and change information of dust particles in the environment. Photoelectric sensor part use Photorectifier and Photoresistance , which can carry on the sampling precisely to the air floating dust . It also uses multi-sensor multi-point measurement techniques, to ensure the accuracy of the data. The experimental data have approved the Instrument has the ability of detection of tdust content .