The utility model discloses a but biaxial stretching's safety barrier, including base, stand, inside book system spring that is equipped with in stand top and the safety protection who convolutes on roll system spring take, stand top outside is equipped with two and becomes the adjacent couple of an angle of 90 degrees, and be equipped with the protective belt with two the central relative position departments that linked up with the stand cross section and export, safety protection area be the same protective belt of two root length degree, be fixed in the guardrail stand with the one end of the protective belt that two root length degree are the same during the installation on, on the book system spring in the guardrail upper end, draw forth two terminals in addition simultaneously, export the outside of drawing forth the guardrail top through the protective belt respectively. Totally closed to safe region, simple structure, easily preparation have been realized to this device under save material's prerequisite.