The invention relates to a power transmission appliance and in particular relates to a telescopic tunnel cable bracket. The telescopic tunnel cable bracket is characterized in that a bearing seat type combination body is arranged at the upper end of a vertical bracket, wherein a bottom seat is arranged at the lower end of the vertical bracket; a shaft sleeve is connected with the combination body through a bearing set; a top seat is arranged at the upper end of a screw rod; the screw rod is connected with a nut body and is inserted into the shaft sleeve from the lower end; an annular boss matched with the shaft sleeve is arranged on the lower end of the nut body; a ratchet wheel shell is arranged outside the nut body; wheel teeth are arranged on the surface layer of the nut body; the shell, the nut body, a positive mechanism and a negative mechanism of the ratchet wheel mounted on the shell, a pawl and a rocking handle form a direction-variable ratchet wheel mechanism; a fastening nut is arranged on the screw rod and is clung to the lower end surface of the combination body. According to the telescopic tunnel cable bracket, the screw rod is moved upwards for fixing the bracket or is moved downwards to demount the bracket; the bottom of the vertical bracket is supported on the ground by the bottom seat; the top of the vertical bracket is supported on the top wall of a tunnel by the top seat of the screw rod; the handle is continuously rocked to finely move the screw rod; the vertical bracket is capable of generating greater pressure and is firmly positioned. The telescopic tunnel cable bracket has the advantages of being compact in structure, convenient to mount, safe to use and reusable.