The utility model relates to the technical field of buildings, in particular to an assembly type detachable mixed stair which comprises a hoisting stair part and a support part, the support part is fixedly connected with an external building, and the upper end and the lower end of the hoisting stair part are fixedly connected with the support part. The hoisting stair part comprises two inclined channel steel beams which are arranged in an inclined manner; wherein the two channel steel cant beams are parallel to each other, a plurality of step plates are fixedly arranged between the two channelsteel cant beams, each step plate comprises a horizontal plate and a vertical plate, the horizontal plates and the vertical plates form a stepped structure, the two ends of the hoisting stairway arerespectively provided with full-length angle steel, and the full-length angle steel is fixedly connected to the lower parts of the channel steel cant beams. The utility model has the advantages of wide material source, simple manufacture, quick installation, detachable recycling, light dead weight and low cost.