The invention discloses a planetary multi-wheel carrier which can be used as a wheel of a ladder climbing wheel, a stair climbing wheelchair or an obstacle crossing vehicle and structurally comprises a sun wheel 1, planet wheels 2, a wheel carrier 3 (a polygonal planetary carrier), small wheels 4, hinge pin assemblies 5, chain wheels 6 and chains 7. A polygonal star-shaped plate is drilled to form the wheel carrier which is also known as the polygonal planetary carrier. The small wheels can be common one-way wheels or universal wheels. A planetary three-wheel carrier, a planetary four-wheel carrier, a planetary five-wheel carrier and a planetary six-wheel carrier are essentially characterized by comprising planetary wheel trains and multi-wheel carriers and belong to the same invention concept, and accordingly patents of the planetary three-wheel carrier, the planetary four-wheel carrier, the planetary five-wheel carrier and the planetary six-wheel carrier are applied simultaneously. Abstract drawings of the planetary six-wheel carrier are shown. A principle includes that when the planetary multi-wheel carrier runs flatly, the planet wheels and the small wheels rotate; when the planetary multi-wheel carrier climbs a ladder, the small wheels rotate at first and reach positions close to a step, and then the wheel carrier revolves; when the planetary multi-wheel carrier descends from a stair, the small wheels rotate until one of he small wheels is suspended, and the wheel carrier revolves, and then continues to revolve after the suspended small wheel is landed. The planetary multi-wheel carrier has the advantages that revolution of the wheel carrier and rotation of the one-wheel wheels can be automatically switched over, so that flat running, ladder climbing and stair descending actions can be smoothly carried out.