The invention provides an elbow-pipe sensor clamping device, and belongs to the technical field of elbow pipe machining clamping tools. The elbow-pipe sensor clamping device is used for improving the machining efficiency and the machining accuracy of an elbow-pipe sensor. The elbow-pipe sensor clamping device comprises two clamping rings, a datum plate, a connection plate, and three positioning blocks. The clamping rings are sleeved at two ends of the elbow-pipe sensor, and a plurality of abutting-against bolts are evenly distributed on the peripheries of the clamping rings and used for fixing the elbow-pipe sensor. The upper ends of the two clamping rings are connected with the connection plate, and the lower ends of the two clamping rings are fixedly connected with the datum plate. The three positioning blocks are placed below the elbow-pipe sensor, the upper surfaces of the positioning blocks are in contact with the circumferential lower portion of the elbow-pipe sensor, and the positioning blocks are fixedly arranged on the datum plate. The elbow-pipe sensor clamping device is simple in structure, convenient to use, and quick and firm in clamping, force is exerted to an elbow pipe evenly in all directions in the clamping process, clamping is more stable and reliable, deformation is reduced, machining efficiency of the end portion and the inside of the elbow pipe is substantially improved, clamping deformation is reduced, and machining accuracy is improved.