Small-caliber steel pipe drill rod applied to working condition of ultra-deep well

The invention relates to the technical field of drill rods, in particular to a small-caliber steel pipe drill rod applied to an ultra-deep well working condition, which comprises a drill column, a connector, a connecting seat and a limiting assembly, the connector is fixedly connected with one end of the drill column, the connecting seat is fixedly connected with the drill column, and the connecting seat is positioned at one end, far away from the connector, of the drill column; the connecting base is provided with a threaded hole matched with the threaded column, the limiting assembly comprises a mounting ring, a first spring and a plurality of limiting columns, the two ends of the first spring are fixedly connected with the mounting ring and the connector correspondingly, the first spring is located in the mounting cavity, the mounting ring is in sliding connection with the connector, and the mounting ring is located in the mounting cavity; and the multiple limiting columns are fixedly connected with the mo