The invention relates to a +/-800 kV extra-high voltage direct current line six-connection three-hanging point strain string replacement method. The method comprises the steps of replacing a first porcelain bottle at the front end of a porcelain insulator string through the cooperative use of a strain separation type front clamp, a strain closing type rear clamp and two hydraulic wire grip devices; replacing any one porcelain bottle in the middle of the porcelain insulator string through the cooperative use of a strain closing type front clamp, a strain closing type rear clamp and two hydraulic wire grip devices; replacing any one porcelain bottle in the middle of the porcelain insulator string through the cooperative use of a strain separation type front clamp, a strain closing type rearclamp and two hydraulic wire grip devices; wherein the operation platform used for replacing the porcelain insulator string is an upper string operation platform or a lower string operation platform.According to the method provided by the invention, the non-power-off maintenance can be realized, and uninterrupted continuous power supply can be realized. The operation platform facilitates the replacement operation of the insulator in the implementation process of the method.