The invention discloses a grouting pipe with bamboo branches and an underground cavity grouting construction method. The grouting pipe comprises a grouting pipe body, wherein a grouting opening is formed in the top of the grouting pipe body, and a plurality of liquid outlet holes are formed in the side wall of the lower part of the grouting pipe body. The grouting pipe is characterized in that theplurality of bamboo branches are arranged in the grouting pipe body in a sleeved mode, branches of the bamboo branches are arranged in the grouting pipe body in a sleeved mode in the axial direction,and the branch tail ends of the bamboo branches extend out of the grouting pipe body from the liquid outlet holes respectively and form a divergent shape towards the periphery. According to the grouting pipe with the bamboo branches and the underground cavity grouting construction method, the grouting pipe with the bamboo branches is placed into the holes during grouting, when the grouting pressure is increased, the slurry can flow to a farther place along the bamboo branches except for seeping out of the liquid outlet holes, after the slurry is solidified, the bamboo branches and surroundingfillers form a whole, the whole is like a big tree rooting underground, and the integrity and the stability of the underground cavity are improved.