The invention belongs to the technical field of mine safety construction, and particularly relates to a roadway floor reinforcing system and a construction method thereof. The roadway floor reinforcing system comprises a plurality of shallow grouting holes, a plurality of medium grouting holes and a plurality of deep grouting holes, wherein the depths of the shallow grouting holes, the medium grouting holes and the deep grouting holes are gradually increased, the shallow grouting holes, the medium grouting holes and the deep grouting holes are all distributed in an array mode, and the shallow grouting holes, the medium grouting holes and the deep grouting holes are distributed in a staggered mode. The roadway floor reinforcing system further comprises a grouting hole packer used for injecting grout into all the grouting holes. By means of the roadway floor reinforcing system and the construction method thereof, a geological anomaly zone, a fracture zone and an argillization floor zone are effectively reinforced, the stability of floor surrounding rock is improved, and the problem of floor heaving is effectively solved; by adopting the grouting hole packer to replace an original grouting steel pipe for grouting, materials are saved, and meanwhile the problem of unfirm floor grouting packing is solved. Thus, the floor grouting reinforcing technology is effective, economical and easy to implement.