Aiming at the different fault characteristics of micro-grid during grid-connected operation and independent operation and the bidirectional characteristics of micro-grid power flow, a micro-grid protection scheme based on improved current phase difference protection is introduced. This scheme uses the voltage at the output terminal of Inverter-interfaced distributed generator as the starting criterion and combines the current phase difference criterion at both ends of the bus bar, ensuring that the micro-grid can accurately distinguish the internal and external faults and remove the faulty line in both operating states. An example simulation is carried out on PSCAD/EMTDC simulation software to verify the effectiveness and reliability of the improved current phase difference-based protection scheme.