A novel smoke detection system using laser is developed to measure the smoke concentration in real-time and quantitatively. A linear relation between transmitted light and scattering light of laser through the smoke is established based on the design of lateral scattering optical structure and the circuit of digital signal processor as a core. According to this linear relationship, the transmitted light is converted to the scattering light, and then the concentration of smoke is calculated. In this way, the computational complexity is reduced, and the problem of measuring low concentration smoke is solved. Finally, compared with existing product, the result shows that this proposed system is simple in structure, stable ,real-time and has good economic benefits.