The invention discloses a clamping device for single-end machining of rigid straight pipes.The clamping device comprises a clamping mechanical arm, a feeding device, a discharging device and a rack, wherein the clamping mechanical arm is used for clamping rigid straight pipes to be machined and conveying the rigid straight pipes to be machined into a machining device, the feeding device is used for conveying the rigid straight pipes to be machined into the clamping mechanical arm and pushing machined rigid straight pipes out of the clamping mechanical arm, the discharging device is used for receiving the machined rigid straight pipes conveyed out by the clamping mechanical arm, and the rack is used for supporting all the devices.The clamping mechanical arm, the feeding device and the discharging device are all fixed to the rack, the feeding device and the discharging device are arranged on the two sides of the clamping mechanical arm, and the machining device used for machining the rigid straight pipes to be machined is arranged at one end of the clamping mechanical arm.The clamping device is simple and compact in structure and low in production cost, and can adapt to machining of various rigid straight pipes, reduce the purchase cost of a factory and improve the production quality of products.