The invention provides a method and a system for judging whether the action of spare power automatic switching is successful or not by a remote automatic bus transfer device. The method comprises the following steps: detecting the inter-station distance of open loop points; calculating according to the distance, the preset judgment spare power automatic switching wait time delay constant value and the preset adjacent device fault removal wait time delay constant value to obtain the maximum time delay when the spare power automatic switching is judged to be successful; judging whether the action of spare power automatic switching is successful or not according to the maximum time delay. After the method and the system are adopted, whether the action of spare power automatic switching is successful or not can be accurately judged by the remote automatic bus transfer device.