The invention discloses a detachable reinforcing steel bar positioning and binding device and a construction method thereof. The device comprises positioning and fixing rods and detachable limiters. Reinforcing steel bars are fixed through the detachable limiters. The positioning and fixing rods are arranged on the four edges of the device correspondingly. The number of the detachable limiters islarger than one, one part of the detachable limiters are installed on the positioning and fixing rods at equal intervals, and the other part of the detachable limiters are arranged at the positions where the reinforcing steel bars are intersected and fixed. The reinforcing steel bars are fixed through the detachable limiters so that the reinforcing steel bars can be fixed to form a grid structure.By means of the detachable reinforcing steel bar positioning and binding device and the construction method, the intervals of the reinforcing steel bars can be precisely controlled, the intervals ofthe device can be adjusted, the binding time of the reinforcing steel bars is saved, and the detachable reinforcing steel bar positioning and binding device and the construction method are suitable for all types of reinforcing bars; the binding work of the reinforcing steel bars does not need to be conducted, the construction time of the reinforcing steel bars is saved, and no binding wires need to be used; and the device can be repeatedly used and is convenient to use.