The invention discloses a construction method of a feeding device for an underground pipeline system. A special construction system of the feeding device for the underground pipeline system is used to construct. The construction system of the feeding device for the underground pipeline system comprises an outer protection tube (2), a water-proof casing (5), a feeding device (4), a welding device and a grouting device (8). The construction method of the feeding device for the underground pipeline system sequentially comprises the following steps of: I: firstly, drilling from the ground surface (101) of the upper part of outer part of the underground pipeline (1) to the direction of the underground pipeline (1); II: then mounting the hollow outer protection tube (2) in the hole drilled by the above process; and III: mounting the water-proof casing (5); and IV: carrying out remote-controlled welding, then unloading the water-proof casing (5) and adding protective packing at a feeding connector (402) by the grouting device (8) so as to protect the feed connector (402). The construction method of the feeding device for the underground pipeline system is comprehensive in technology, remarkable in effect, convenient to construct and operate and high in technical maturity, and has predictable great economic value and social value.