The invention relates to a dynamic insulation test method and system for a fast mechanical switch. The test method comprises the following steps: controlling the fast mechanical switch to open; withinthe action time of the fast mechanical switch, applying surge voltage to the fast mechanical switch; and recording related performance parameters of the fast mechanical switch. The dynamic insulationtest method triggers application of surge voltage to the fast mechanical switch in a very short time within the action time of the fast mechanical switch through strict control timing sequence, thereby realizing voltage withstand test of the fast mechanical switch, and solving the problem that the dynamic insulation performance of the fast mechanical switch cannot be tested in the prior art.