The invention belongs to the field of a tool for power transmission lines and specifically relates to a U-shaped screw rod insulation installer, which is an insulation tool for live-line installation and disassembly of a straight line holder for a 66 KV power transmission line. The installer comprises a main body and a locking structure. The main body has two parallel side bodies having a certain thickness; the bottom portions of the two side bodies are connected, and a strip-hole channel is formed in the middle; the inner side surface of at least one side body is provided with a U-shaped clamp groove for placing a U-shaped screw rod; and the locking structure comprises a telescoping ejector rod bolt arranged in the strip-hole channel, and a screw rod passing through the bottom portion of the side bodies and connected with the ejector rod bolt, wherein the other end of the screw rod is connected with an insulation rod. According to the insulation installer, the straight line holder can be installed, disassembled and replaced without cutting off the power, thereby improving operability range, increasing live-line work items and effectively improving work efficiency.