The invention provides a dismountable ladder, which consists of at least three ladder sections, wherein each ladder section consists of two support rods and at least one reinforcing rod; the two support legs have the same length, and are arranged in a way of forming an isosceles trapezoid shape; the two ends of each reinforcing rod are respectively fixed on the corresponding two sections of support rods; the support rods arranged on the corresponding two connected ladder sections are in mutual butt joint in the length direction of the support rod; and any two adjacent ladder sections are detachably connected. Therefore the dismountable ladder solves the problems that the existing ladders are of integral structures; in the use process, the ladders are often too long or too short, so that the use is inconvenient; and the ladder of the integral structure has very long length, is inconvenient to store and can only be put in outdoor positions to be exposed in the wind and the sun, so that the aging of the ladders is accelerated, and the service life of the ladder is greatly reduced. The dismountable ladder belongs to the field of a building tool.