The invention belongs to the technical field of tunnel underground excavation construction, and specifically relates to a construction method for replacing initial support arches of a small spacing shallow-buried tunnel. An emergency reinforcement treatment system including compaction of earthworks with height to the position of the upper bench skewback, construction of long glass fiber anchor rods in tunnel faces, spraying of concrete and temporary sealing of inverted arch initial supports, construction of vertical steel supports, ground waterproof construction, secondary lining reinforced concrete reinforcement in a tunnel, ground grouting and filling construction is adopted, an advance support system combining advanced pipe-greenhouse supports and advanced small conduit supports is adopted, and the 3m-closed construction method during construction is adopted, so that safety during construction is greatly improved, and safety of life and property is ensured.