A clamping seat includes a pipe seat, a movable clamp and a fixed clamp. The pipe seat includes an inner pipe space and an outer pipe space to insert the inner pipe and the outer pipe. The pipe seat includes a side opening beside the inner pipe space and a side space beside the outer pipe space. The movable clamp includes an arc block beside the side opening, and a screwing member pressing the arc block into the inner pipe space then to press and fix the inner pipe. The fixed clamp includes a clamping plate in the side space, and a tightening bolt pressing the pipe seat against the clamping plate, allowing the clamping plate to press the outer pipe.