Frequency Modulated Continuous Wave(FMCW)laser ranging has many advantages such as no measuring blind area, noncontact measuring and absolute distance measurement. However the measuring precision of FMCW laser ranging is limited by the modulation nonlinearity of tunable laser. Hence, this technology is not widely used in the field of precision measurement. The precision of FMCW laser ranging was affected by the nonlinearity of laser frequency modulation. The method of dual interferometry FMCW laser ranging was proposed. The distance of the target was equal to the ratio of the interference fringe of two interference systems. Using the method, the influence caused by the nonlinearity of laser frequency modulation was eliminated. The resolution and repeatability precision of the system was 65 μm and 15 μm respectively. The system has the following advantages. There is no need to measure the wavelength of the laser or lock the frequency of laser. And the structure is simple. This system has a wide application prospect in industrial large scale measurement, space technology, and surveying.