The present invention discloses a device and method for adjusting tension of a steel wire rope of an ultra-deep vertical shaft at a hoisting-container-end. The device includes two stages of steel wire rope tension adjusting devices provided on a hoisting container, where a primary steel wire rope tension adjusting device includes left and right steel wire rope tension adjusting devices that are symmetrically arranged, and a secondary steel wire rope tension adjusting device is provided below the primary steel wire rope tension adjusting device. By use of two stages of steel wire rope tension adjusting devices, tension on four steel wire ropes can be adjusted to equalize the tension, thus meeting the requirement for tension equalization in a hoisting process. The four steel wire ropes are equally divided into two groups. Tension of two steel wire ropes is adjusted by rotating a primary drum around which the two steel wire ropes are wound, and then tension of the four steel wire ropes is adjusted by rotating a secondary drum around which the multiple steel wire ropes are wound, thus achieving a final purpose. The device of the present invention has a simple structure, and is conveniently mounted and easily detached. The tension is automatically adjusted by rotating the drums. This solution is novel and has wide application.