The invention relates to the technical field of building construction, in particular to an inter-supporting trestle system combined with an inner supporting system and a construction method. The inter-supporting trestle system comprises an inner supporting system and an inter-supporting trestle, wherein the inner supporting system comprises plate supports, a plurality of supporting stand columns are arranged between the plate supports, the inter-supporting trestle is obliquely connected between the adjacent plate supports, and passing ports are formed in the plate supports; the construction method of the inter-supporting trestle system comprises the following steps of arranging the inner supporting system, digging a soft soil layer on the surface of a soil slope between the adjacent standcolumns, backfilling dry hard soil, rolling the soil layer, pouring a coagulation layer, excavating slope toes, building a soil blocking brick wall, building a support frame, laying a template, and pouring concrete into the template. According to the inter-supporting trestle system combined with the inner supporting system and the construction method, the trestle does not need to be additionally constructed, the investment construction amount is reduced, the inter-supporting trestle and the inner support system form a through continuous channel, a transportation machine penetrates into the bottom of a foundation pit, the soil fed by an excavator is received, then transferring is carried out, and the earthwork excavation work efficiency is improved.