The invention relates to a detachable rotary horizontal all-insulation arrester with a disconnector. The arrester comprises a cross arm mounting bracket, an arrestere mounting underframe, an arrester body and an arrester umbrella-crossing insulation cover, wherein the cross arm mounting bracket is installed on a pole cross arm, the arrester mounting underframe and the cross arm mounting bracket are firmly hinged, the arrester body comprises an arrester grounding end and an arrester high-voltage end, the arrester grounding end is fixedly connected with the arrester mounting underframe, and is provided with an arrester grounding electrode, the arrester grounding electrode is electrically connected with a cross arm base grounding end through the disconenctor, the arrester high-voltage end is provided with an arrester high-voltage binding post, the outer part of the arrester high-voltage end is wrapped with the arrester umbrella-crossing insulation cover, and a down lead of an overhead line passes through the arrester umbrella-crossing insulation cover to be electrically connected with the arrester high-voltage binding post. The invention adopts the horizontal rotary arrester which is additionally provided with the umbrella-crossing insulation cover, which has the characteristics of convenience in maintenance and good safety performance.