The invention relates to the field of geological exploration, in particular to a multifunctional geological exploration drill bit. The drill bit comprises a drill bit body, a sealing plug, a mountingmechanism, a connecting mechanism, a compression mechanism, a screw rod, a reset mechanism, a limiting mechanism and limiting blocks; the screw rod is mounted on the top of the drill bit body and is in threaded connection with the compression mechanism in the mounting mechanism, the screw rod moves to make the compression mechanism slide in the mounting mechanism, and gas in the mounting mechanismis compressed, so that the gas pushes the limiting mechanism to slide downward in the mounting mechanism, the limiting mechanism slides into the connecting mechanism on the top face of the drill bitbody, and the limiting mechanism is clamped to the connecting mechanism. During use, the mounting mechanism drives the drill bit body to rotate, and the limiting mechanism fixes the drill bit body, sothat the position between the drill bit body and the mounting mechanism is fixed, and the drill bit body is prevented from being reserved in the underground. The sealing plug mounted on the top of the compression mechanism is taken out, the compression mechanism is opened, and the gas in the mounting mechanism is discharged, so that the limiting mechanism is separated from the drill bit body, andconvenience is provided for people to replace the drill bit body.