The utility model provides an anticollision central separator opening guardrail with adjustable length, is favorable to on whole length direction improving opening guardrail and central separator open -ended suitability, its characterized in that, and including a plurality of sections frame units, through the connection of coupling assembling split ground between the adjacent frame unit around but, coupling assembling is the coupling assembling of the adjustable length of axial, the anterior segment girder of coupling assembling's anterior fixed connection anterior segment frame unit, the back end girder of coupling assembling's rear portion fixed connection back end frame unit.