The utility model discloses a cable wire formula hydraulic pressure tension device for transmission line, equipment includes: hydraulic power unit places on the iron tower cross arm for provide hydraulic oil for the pneumatic cylinder, the pneumatic cylinder, through high pressure fuel pipe with hydraulic power unit is connected to acquire hydraulic oil from hydraulic power unit, preceding anchor head comprises preceding jack catch and preceding board, works in turn with the back anchor head and presss from both sides tight cable wire, back anchor head comprises back jack catch and back board, works in turn with preceding anchor head and presss from both sides tight cable wire, and the cable wire, one end is connected with the back anchor head with preceding anchor head, and the other end is connected with the wire. The utility model has the advantages of adopt hydraulic drive, through two -way infinitely variable closed -type hydraulic system's design, output power satisfies tight line construction job requirements, disposes simultaneously and runs line emergency braking function, through special loop design, can realize tight line motion control to can maintain the system pressure when the hydraulic circuit trouble, prevent to run the line occurence of failure, improve site operation safety.