Operating rang is the chief content calculated in the design of laser detection system.Based on the technology of imaging laser detecting system,the relationship between the laser propagation and atmospheric parameters like visibility and refractive index structure constant was discussed while analyzing laser propagation effects in atmosphere.Taking optical scintillation and aperture averaging into account,the operating range model shown by minimum detection power or illumination was discussed while specific detection possibility.The quantitative relation between received power and detection distance was studied with numerical simulation algorithm with typical instance.The calculation results show that the vehicular laser warning device of several mille watts per square centimeter insensitivity can detect laser signal of target reflection and atmospheric dispersion in common tactics circumstance,which can provide a guideline for the development and design of the system.