The invention provides a grouting curtain drilling structure and a construction process thereof, and relates to the technical field of mine curtain grouting. The grouting curtain drilling structure comprises a plurality of straight grouting holes formed along a curtain line. A plurality of branched grouting holes communicating with the straight grouting holes are further formed in the peripheries, in the height direction, in the straight grouting holes, and the directions of the branched grouting holes radiate and extend towards the peripheries. After grouting, in the curtain line direction, the exposure rate of high-angle water guide cracks can be increased, or water guide cracks in any angle can be exposed. The grouting curtain drilling structure and the construction process have the technical effects that compared with the prior art, the exposure rate of the high-angle water guide cracks can be greatly increased, or the water guide cracks in any angle can be exposed, and therefore the grout dispersion radius is increased, the grouting effect is guaranteed, the number of the straight holes and the drilling workload are greatly reduced, the cost of investment of the mine party is reduced, and great economic benefits and social benefits are achieved. Due to the fact that the distance between the straight holes is increased, it is possible that a tunnel inner curtain grouting manner is adopted for water plugging in mines in lofty mountains and steep hills.