The invention discloses a solid-stone bare-rock riverbed trestle used for the deepwater high-pier long-span bridge construction and a construction method thereof. The trestle includes a trestle body and a horizontal work platform located on the front side of the trestle body. The trestle body includes a lower-portion support structure, a main beam and a bridge deck; the lower-portion support structure includes one or more steel abutment anchoring piles, the lower portions of the steel abutment anchoring piles are anchored to a bare-rock riverbed, the front end of the main beam is supported ona steel cofferdam, the rear end of the main beam is supported on a shoreside surpport platform, and a concrete pumping pipe is placed on the bridge deck; the horizontal work platform is set up on thesteel cofferdam and is connected with the main beam, and each steel abutment anchoring pile includes a groined steel abutment and a steel abutment anchoring structure. The method includes the steps of1, construction of the steel abutment anchoring piles, 2, erecting of the main beam and 3, paving of the bridge deck. The solid-stone bare-rock riverbed trestle is reasonable in structural design, easy to construct and good in use effect, the steel abutment anchoring piles are stably supported on the bare-rock riverbed, the front end and rear end of the main beam are supported on the steel cofferdam and the shoreside support platform respectively, and labor and time are saved.