The invention relates to a rail bolt type telescopic adjustable anti-climbing support, which is characterized in that bolt groovesare formed on the inner wall of two sides of the anti-climbing box, apressure spring is fixedly connected witheach bolt groove, one end of the trapezoidal bolt is inserted into the bolt groove and is connected with the pressure spring; the telescopic frame of astressedtop plate is inserted into acavity, the bottom of the telescopic frame of the stressed top plate is provided with a straight rack, two F-shaped sliding blocks and a reset gear are arranged in the middle, the outer vertical edge and the inner transverse edge of the F-shaped sliding block are respectively a one-way saw tooth and a reset straight rack, the reset gear is meshed with the reset straightrack of the F-shaped sliding block, and the outer end of the trapezoidal bolt on the wall of the anti-climbing box is meshed with the one-way saw tooth of the F-shaped sliding block to form a self-lock; the auxiliary gear at the bottom of the anti-climbing box is meshed with the straight rack at the bottom of the stressed top plate telescopic frame. The rail bolt type telescopic adjustable anti-climbing support can adjust the size of anti-climbing supportthrough the meshing between the trapezoidal bolt and the one-way saw tooth, and has the advantages of good universality, strong structural stress resistance, free expansion and adjustment, convenient maintenance and replacement and the like.