Disclosed is a fully detachable trocar, comprising: a cannula; a support connected to one end of the cannula; a channel passing through the cannula and the support along an axial direction; an air-inflated structure arranged on the support and communicated with the channel; an air valve for controlling the air-inflated structure to turn on and off; a primary sealing component for sealing when a device is used; and a second sealing component for sealing when no device is used; the primary sealing component, the second sealing component and the support are connected in a sealing manner from top to bottom in sequence, and the primary sealing component can be independently separated from the second sealing component which can be independently separated from the support, so as to provide multiple methods for taking out tissues.