The invention discloses a surgical navigation and mechanical arm device for craniocerebral puncture. The device comprises a three-dimensional CT scanning device, a handheld scanner, a computer system,a mechanical arm control system and a mechanical arm execution system, wherein the three-dimensional CT scanning device, the handheld scanner, the mechanical arm control system and the mechanical armexecution system are connected with the computer system; and the mechanical arm control system is connected with the mechanical arm execution system. Moreover, the invention also provides a positioning method of the device. The method mainly comprises the following steps of obtaining a target point needing a minimally invasive surgery through preoperative brain CT, performing fixed point markingon the brain, performing scanning by using a probe, planning a surgery track, and registering the probe position of the mechanical arm and a fixed point mark in an image space. After registration, a doctor can obtain coordinates of any feature point of a human-computer interface by clicking the feature point, and the mechanical arm moves the surgical tool after receiving the coordinates of the feature point, so that the doctor can accurately find target features.