The invention provides a pneumatic fastener gun for internal fracture fixation. The pneumatic fastener gun comprises a gun body, a gun grip, a protective device, a fastener clamp device and a pneumatic device, a button is arranged at the head position at the joint of the gun grip and the gun body, and the tail of the button is embedded into the gun grip. The pneumatic fastener gun for internal fracture fixation is characterized in that the protective device comprises a protective cover and a protective cover connecting rod connected with the protective cover, the protective cover covers the head of a fastener passage device, a through hole is formed in the middle of the protective cover, and the tail end of the protective cover connecting rod contacts with the tail, embedded into the gun grip, of the button. The pneumatic fastener gun for internal fracture fixation has the advantages that the pneumatic fastener gun is simple and convenient to use and accurate when being used for fixing the fracture part and is capable of fixing the minimally invasive part effectively; the structure that the protective cover is matched with the button is equivalent to two triggering devices, a user who wants to shoot a fastener needs to enable a gun barrel to be aligned with the surface of the facture part by pressing while pressing the button, and accordingly, double protection effect and more safety in use are achieved to avoid misoperation during surgery.