The invention discloses a three-post horizontally turning type extra-high voltage series compensation parallel-connection isolation switch, which comprises three monopoles, wherein the three monopoles have the same structures and realize the synchronous operation through electric linkage, two isolation fractures are formed in the horizontal direction between a main conductive tube and a static contact during brake separation, an arc contact, an arc contact plate loop and an arc extinguish chamber loop are connected in series, and form a three-loop parallel connection structure with an auxiliary contact loop and a main loop, bus conversation current is switched off or switched on through a vacuum arc extinguish chamber, the main conductive tube firstly rotates and then does turning movement during brake closing, the main conductive tube firstly does turning movement and then rotates during brake separation, and the vacuum arc extinguish chamber pulls a pulling fork of the vacuum arc extinguish chamber through driving a touch rod by the main conductive tube for realizing the brake separation and closing action of the vacuum arc extinguish chamber. The invention has the characteristics of stability, reliability, small operation force, little brake closing impact, high through flow stability, strong switching-on and switching-off capability, good arc extinguish effect, good corrosion prevention performance, long service life and the like.