A method for detecting a time synchronization ability of the real-time measuring device based on a time variable is provided. On a premise that the real-time measuring device correctly receives time service signals, the method aims at detecting time synchronization signal application ability of the real-time measuring device, and involves a purely resistive loop comprising a value transferring device and a time controllable switch. The method, via a time synchronization performance thereof, relatively completely reflects the time synchronization signal application ability of the device within a value transfer requirement. The method is a development upon power station time synchronization time service signals and transmission accuracy detection and an improvement of power station time synchronization detection procedures. The method facilitates improving real-time analysis and monitoring abilities of a power station and a power grid to a primary device and a primary system.