The invention relates to the technical field of curtain grouting, in particular to a grouting device for gravel-cobble strata. The grouting device comprises outer pipes, outer pipe sealing devices, inner pipes and inner pipe sealing devices, wherein the inner pipes and the inner pipe sealing devices are arranged inside the outer pipes, and each inner pipe is provided with two inner pipe sealing devices; the pipe section located between every two inner pipe sealing devices is an inner pipe grout outlet section, and each inner pipe grout outlet section is provided with inner pipe grout outlets. The grouting device is characterized in that a plurality of orientated opening sets are formed in the wall of each outer pipe in the axial direction of each outer pipe and respectively comprise at least one pair of orientated openings formed in the periphery of one outer pipe, the radial direction of the periphery of any one outer pipe is adopted as the basis radial direction, and all the orientated openings are formed within the range of 0-45 degrees of the basis radial direction. According to the grouting device, the diffusion direction of grout is controllable, the grouting amount is reduced, the grouting efficiency is improved, and the reliability of curtain lap joint is improved. The invention further relates to a grouting method adopting the grouting device. Curtains perpendicular to the seepage direction can be easily formed through the grouting method.