Folding steel barrier, the effectual damage problem of engineering machine tool to the guardrail of having solved, it includes guardrail and lower guard bar, and it is articulated to go up guardrail and lower guard bar, and upward guardrail and lower guard bar go up the rigid coupling has the sleeve pipe, overlaps the intraductal screw of wearing to be equipped with, guardrail and lower guard bar articulated structure in the component, and wherein the sleeve pipe includes first sleeve pipe, rigid coupling third sleeve and rigid coupling the second sleeve pipe on last guardrail on lower guard bar of rigid coupling on lower guard bar, threaded hole is seted up to first sleeve pipe, the outmost plane that is of first sleeve pipe, and the first sleeve pipe second floor is equipped with the terminal surface ratchet, and the inlayer of first sleeve pipe is supporting platform, the intraductal sliding connection of second cover has a slider, the slider left end be equipped with with first sleeve pipe on ratchet matched with terminal surface ratchet, the utility model discloses simple structure, firstly convenient to use has guaranteed the validity of the daily protection of guardrail, has secondly practiced thrift the expense that ann tore open and maintained, has improved production efficiency, saves mechanical use fee and other fees, has reduced construction costs.