An endoscope, including: a handle, a sheath tube, an endoscopic cannula, and a tensioning mechanism. The sheath tube includes a first axial guide hole and a first joint pin disposed in the first axial guide hole. The handle includes a second axial guide hole and a second joint pin disposed in the second axial guide hole. The first joint pin matches and is directly connected to the second joint pin. The sheath tube matches and connects to the handle. The handle includes a cavity and the tensioning mechanism is disposed in the cavity. The endoscopic cannula includes a flexible part extending out of the sheath tube and a rigid part fixed in the sheath tube. The flexible part includes a steering wire. The first joint pin is connected to the steering wire. The tensioning mechanism is connected to the second joint pin.