The invention provides a ring network communication test method and test system of a localization device. The test method comprises: test data are injected into a ring network of a to-be-tested localization device; messages sent out by all sub units in the to-be-tested localization device are detected; according to the messages sent out by all sub units and the test data injected into the ring network, whether communication of each sub unit is abnormal is determined. According to the invention, the test data are injected into the ring network of the to-be-tested localization device; all sub units carry out identification and analysis on the received data; if the false data can be identified and abandoned, the communication function of each sub unit is determined to be normal; if any sub unit can not identify the false data and forwards the data to other sub units, the communication function of the sub unit is determined to be abnormal. Therefore, testing of the ring network communication capability of the localization device is realized; and the reliability of relay protection equipment communication is ensured.