The vortex light field has helically shaped wavefront and phase singularities where each photon carries orbital angular momentum (OAM). Its unique properties allow the vortex light field to spatially distinguish incoherent scattered light from coherent non-scattered light, which thus can therefore be used as a spatial filter element. And in the strong scattering environment, this spatial filtering effect is particularly remarkable. The principle of spatial filtering was analyzed and studies of vortex light field in strong scattering environment were introduced. The underwater lidar ranging experiment using the vortex light field was designed to prove that the vortex light field can improve the accuracy of the underwater lidar through its spatial filtering in strong scattering environment. And with strong scattering, this spatial filtering improves the range accuracy more significantly.