The invention relates to a double-joint sickle-shaped knife for gastroendoscope minimally invasive surgeries. The knife comprises a knife bit, a knife holder, a knife body, an outer bushing, a conducting wire, a handle and a sliding rod. The knife bit is connected with one end of the knife holder through a cross joint, and the other end of the knife holder is connected with the head end of the knife body through a longitudinal joint. The outer bushing is sleeved on the outside of the knife body and capable of sliding along the knife body. The tail end of the knife body is connected with one end of the handle, and a sliding rod for adjusting the cross joint is arranged on the handle. The conducting wire is conductive, one end of the conducting wire is connected with the knife bit and penetrates the knife holder, the knife body, the handle and the sliding rod successively. The other end of the conducting wire is connected with a power interface. By means of the knife, the endoscope knife surface multi-angle moving, including the knife surface and mucosal tissue parallel cutting condition, can be achieved, and the knife surface angle is not limited by an endoscope lens, so that the speed and the quality of endoscope operations are improved apparently, and subsidiary injuries might occurring to peripheral tissues are reduced to furthest.