The invention discloses a full optical pulse compression laser radar system and a range finding method for object detection in a continuous scattering medium, relating to the pulse compression laser radar system and the range finding method. The full optical pulse compression laser radar system comprises femotsecond laser which outputs pulse laser; in a transmission direction of pulse laser, the femot second laser, a cascade linear chirp fiber Bragg raster, a first optical circulator, a single mode optical fiber and a flat gain filter are arranged in a front end of an optical emission device; pulse laser is marked as an object reflection light signal after reflection; the optical reception device receives the object reflection light signal; in the signal transmission direction, a second optical circulator and a negative dispersion optical fiber Bragg raster are arranged on the rear end of the optical reception device. The full optical pulse compression laser radar system and the range finding method for object detection in continuous scattering medium utilize a cascade chirp fiber Bragg raster to generate a large time bandwidth product modulation signal, and adopt a negative dispersion optical fiber Bragg raster to carry out pulse compression processing in order to make range finding precision reach a millimeter magnitude. The full pulse compression laser radar system and the range finding method are applicable to the design and set up of a radar system.