Abstract: A positioning joint for a folding ladder comprising a first joint member, a second joint member disposed between the first joint member, and a hollow shaft inserted into central holes of the first and second joint members. The joint further includes a turning plate disposed on an inner wall of a first disc portion of the first joint member, a crank-shaped strip, and a spring mounted around the hollow shaft. A push knob is inserted into the hollow shaft, and a pin is inserted into a pair of axially elongated holes in the hollow shaft and into a pin hole in the push knob. The crank-shaped strip has a pair of small projections adapted to be inserted into engaging holes of the first and second joint members as well as a pair of large projections adapted to be inserted into the first and second joint members and the turning plate. The crank-shaped strip also has a central portion fixed between the hollow shaft and the spring.