The invention belongs to the technical field of ultra-high voltage power transmission, in particular to a method for improving the converted current switching capability of an ultra-high voltage open alternating current isolating switch. Auxiliary circuits are added on a main contact to switch converted current, and isolating switches are used to guide the operation of electric poles, so that the converted current switching capability of the isolating switches can be greatly improved, and the use requirements for connecting the isolating switches in parallel can be met. Thus, by using the method, the converted current switching capability is greatly improved, the requirements for connecting the isolating switches in parallel are easily met, the influence of electric arcs is almost completely eliminated, the operation and the control of the isolating switches are greatly simplified, the cost is lowered and the reliability is improved.