The utility model relates to a GW4-252III type dual-pole central facture horizontal rotary outdoor three-phase high-voltage alternating current isolating switch, which comprises three single electrodes, a main blade horizontal driving rod and an earthing blade horizontal driving rod. Each single electrode comprises a main conducting device, a pillar insulator, an underframe device, a main blade driving device (9) and the like. The main blade driving devices (9), a left earthing blade driving device and a right earthing blade driving device are all arranged above bearing blocks (1) which are fully sealed, and an earthed switch (5) adopts a straight-wheeled outdoor high-voltage alternating current earthed switch. As transmission on the lower portion of the bearing block (1) is changed into transmission on the upper portion thereof, driving reliability and stability are strengthened greatly; and the full-sealed bearing blocks at two ends of the base have fine waterproof and dustproof actions. The isolating switch has the advantages of stable make-and-brake action, reliable performance, low make impaction, low cost, long service life and the like.