A new atmospheric remote sensing detection system, White-light Lidar, was designed and a detection method based on radar mode of long-path differential absorption spectra was developed. The main structure of the White-light Lidar and time-resolved spectrum detecting technology were introduced. The feature of the femtosecond laser pulses propagating for filament formation in atmosphere and white-light supercontinuum were expounded. Using the White-light Lidar system, the long-path differential absorption spectra of oxygen molecules in the range of 685~694 nm and 759~769 nm were detected. The measured results are in good agreement with the fitted spectra of Hitran database, which indicates the correctness of the remote sensing detection system of White-light Lidar and the feasibility of the