The invention relates to a multi-arch tunnel construction method, and belongs to the field of tunnel construction. A middle pilot tunnel and a middle partition wall of a multi-arch tunnel are both in a straight wall type, the middle partition wall is arranged on the side, close to the middle pilot tunnel, in the middle pilot tunnel, and after construction of the middle partition wall is completed, one side of the middle partition wall is tightly attached to the inner wall of the middle pilot tunnel. Due to the fact that one side of the middle partition wall is tightly attached to the inner wall of the middle pilot tunnel, when concrete pouring is conducted on the middle partition wall, concrete pouring can be conducted only by providing a middle partition wall formwork sealing formwork on the other side, and the formwork erecting time and cost are saved. After construction of a section of the middle partition wall is completed, a large operation space still exists in the middle pilot tunnel, synchronous construction of other procedures is facilitated, and the construction efficiency can be improved. After construction of the middle partition wall is completed, earthwork backfilling or steel support installation is not needed, and the cost and the working time are saved. In the main tunnel excavation process, the middle partition wall provides counter force through the wall of the middle pilot tunnel, the method is more reliable, and the construction safety is improved. The multi-arch tunnel construction method has positive influences on the multi-arch tunnel construction safety, quality, progress and cost.