The invention discloses a construction method of a deep burying center ditch for a tunnel in an extremely cold region; before construction of an inverted arch of the tunnel, advanced construction is performed on the deep burying center ditch via a simple inverted-arch trestle, and then the inverted arch is constructed via a mobile inverted-arch trestle; the method comprises the specific steps of I, controlling blasting construction via boreholes, vertically distributing boreholes to perform deep-hole blasting, excavating by deck blasting, wherein all ditch blastholes incline out of the tunnel; II, excavating a ditch with a small excavator to a designed elevation; III, clearing ditch false dregs and ponding; IV, constructing a foundation; V, burying and installing a culvert; VI, performing graded backfilling; VII, casting thermal insulation concrete; VIII, tiling insulation plates. The problems of the prior art are effectively solved, such as difficulty in construction organization, low working efficiency, slow construction progress, high cost, and great disturbances to surrounding rock, and good service effect is achieved.