The invention discloses a construction method of a tunnel pile of a platform structure. A stratum is strengthened through front pre-grouting, a force transforming path of a cross tunnel is converted into a cross tunnel roof-an initial support roof of a main structure-a top beam or a top longitudinal beam-a concrete-filled steel tube column and a side pile-a bottom longitudinal beam and a strip foundation-a stratum, earth excavation is performed sequentially from top to bottom to form a strong support system, and the technical effect that stratum deformation is effectively controlled through high support resistance can be achieved; though underground excavation of a tunnel pile is adopted for excavation construction, excavation construction is small in work amount, and risk in controlling stratum settlement is greatly lowered; construction speed of the platform structure is effectively increased, time cost, labor cost and material cost are effectively lowered, construction period of subway projects is greatly saved, impact of construction on surrounding environment and adjacent building structures is reduced, and project cost can be greatly reduced.