The invention relates to an isolation device of a platform compensator for a sliding plug door. The isolation device comprises a lock cylinder, an isolation sheet, an isolation stopping block, a connection rod and an isolation spring bolt assembly. An elastic piece drives a connection plate and a spring bolt to reset in a rotating mode. The isolation sheet is installed on the lock cylinder and fixed relative to the lock cylinder. The isolation sheet and the connection plate are connected through the connection rod. When the isolation device is in the initial state, the isolation sheet rotates clockwise to cross the dead motion spot between the isolation sheet and the connection rod; and when the isolation device is in the isolated state, the lock cylinder drives the isolation sheet to move anticlockwise to an upper limiting portion to make contact with the isolation stopping block, and the spring bolt is in a locked state. The isolation device has the beneficial effects that when the isolation device is in the initial state, as the isolation sheet rotates clockwise to cross the dead motion spot between the isolation sheet and the connection rod, the whole isolation device bears a downward pre-tightening force under the joint action of a lower limiting portion of the isolation sheet and the elastic piece, the effect that components of the isolation device are free of bounce and disengagement when a vehicle body is in a vibrating state is ensured, and reliability is improved.