The dual wavelength and dual pulse light source with wavelengths of 448.1 nm and 449.15 nm have potential application in differential absorption lidar (DIAL) for measuring NO2 concentration in atmosphere. A dual wavelength (896.2 nm and 898.3 nm) and dual pulse Cr∶LiSAF laser output is achieved adopting the high pressure and square wave to drive the electric light Q-switch. Using one LBO crystal as the frequency doubling crystal, a dual wavelength (448.1 nm and 449.15 nm) and dual pulse laser is got. The output for one wavelength is about 13.7 mJ, the line width is less than 0.02 nm, and the time interval for two pulse in one pumping is about 62 μs.