Well drilling speed increasing device with composite drill bit

A well drilling speed increasing device with a composite drill bit comprises a drill column, a pilot bit and a reaming bit. A cone of the reaming drill bit is located at the tail end of the drill column, the pilot drill bit and the drill column are coaxially arranged, a cone of the pilot drill bit is located below the reaming drill bit, a turbine motor is arranged in the drill column and used for driving the pilot drill bit to rotate, the turbine motor is driven by drilling fluid, and the side wall of a rod portion of the pilot drill bit is in sliding connection with the inner wall of the drill column through multiple rows of annular balls. The rod portion of the pilot bit is connected with a rotating shaft of the turbine motor through an elastic telescopic structure, and the elastic telescopic structure is used for pushing the pilot bit to be axially away from the reaming bit. The pilot bit of the device can axially move relative to the reaming bit, so that the two levels of bits are both in compression cont