The invention provides a modular steel structure house and a construction method thereof. The modular steel structure house comprises frame structures and a plurality of supporting
steel plates; the two frame structures are oppositely installed and fixedly connected with each other through the supporting
steel plates. According to the house, by splicing supporting rods and connecting frames different in shape, the area of the built house can be freely controlled; when the supporting rods and the connecting frames are connected, the supporting rods and the connecting frames are in
abutment joint with each other at first and then are locked through bolts, before installation, all the supporting rods are separate rod bodies, and therefore the transportation pressure is reduced; when the supporting
steel plates are installed, the shielding surfaces of the supporting steel plates alternately face inwards and outwards, and therefore the resistance performance of the supporting steel plates under the transverse applied force is improved; it is conducive to greatly shortening the construction period by adopting modular materials for construction.