To solve the problems that current protection operational state evaluation is ineffective to reflect the real-time operation of protection and accomplish online analysis and evaluation for protection system automatically, an online evaluation method of protection operating state is proposed. Based on the concept of measuring intercept, a fault line identification method is introduced, which avoids the influence of transition resistance on the distinction between measured impedance and real impedance from fault point to relay location. Evaluation method for operating state of protection system is built. Layered transmission of real-time operation probability message is realized through the establishment of the protection information matrices. The evaluation of protection “four characteristics” is done using operation probability of fault elements and non-fault element. Simulation of protection operation evaluation on different fault conditions in actual grid validate that the proposed method can identify the fault line rapidly and is effective and reasonable to evaluate operation state of the protection.