The invention discloses a tunnel cross-section primary lining construction process. The tunnel cross-section primary lining construction process includes steps of S1, chiseling away the lower portionsof middle partition walls according to 6m sections, inverting primary supporting concrete in secondary lining thickness ranges, cutting off the lower portions of grid main reinforcements and formingfilling portions; S2, laying waterproof layers, binding reinforcing steel bars, pouring inverted arch concrete, pouring the filling portions and forming inverted arches; S3, detaching two ends of eachmiddle partition plate in 1m ranges, detaching the primary supporting concrete in the ranges of the tops of the middle partition walls and cutting off the grid main reinforcements; S4, erecting transverse formwork supports, mounting arch centers and formworks, pouring side wall and arch concrete and forming second linings; S5, erecting temporary supports, detaching temporary remaining braces, sequentially breaking down and detaching the middle partition walls and the middle partition plates from top to bottom and from edge to center and completely detaching temporary supporting. The tunnel cross-section primary lining construction process has the advantages that the residue earth generation volumes at earlier stages can be effectively reduced, the influence degree of residue earth outwardtransport on the progress can be lowered, and secondary lining which is a critical working procedure can be constructed in an acceleration manner in advance.