The invention belongs to the technical field of 
medical instruments for 
surgery and particularly relates to a medical brain 
drill. The medical brain 
drill is characterized by further comprising a limiting device, the limiting device is provided with a 
drill bit limiting hole and a drilling 
machine connecting rod, one end of the 
drill bit penetrates through the 
drill bit limiting hole to be fixedly connected with the limiting device, the other end of the 
drill bit is fixedly connected with the drilling 
machine connecting rod, a thread is arranged at the front end of the drill bit, an iron drill bit connecting shaft is arranged at the front end of a drilling 
machine, a groove matched with the drilling machine connecting rod is formed in the center of the iron drill bit connecting shaft, a 
magnet is arranged in the groove, a sterile sleeving bag is arranged out of the drilling machine, an elastic opening is formed in the sterile sleeving bag and located in the iron drill bit connecting shaft, and the drill bit is located on the exterior of the elastic opening. The medical brain drill has the advantages that the medical brain drill does not need to be used in cooperation with a positioning device of a stereotactie 
surgery instrument, potential dangers caused by invalidation of the limiting device are eliminated, and the medical brain drill is 
safer and more reliable; the drill bit is connected with the drilling machine through magnetic force, dismounting and mounting are convenient, and the drill bit cannot disengage from the drilling machine in the 
surgery process.