Micro-grid is next generation of distribution system. The paper mainly investigates fault diagnosis issue of Micro-grid by using advanced Petri net technology. The paper puts forward diagnosis model of micro-grid based on Timed-colored Petri Net embedded object-oriented. The approach encapsulates each protection information, the associated breaker information and electrical components information and creates corresponding database tables. When the protection or breaker action occurs, through the means of communication to obtain the corresponding action information, use protection information as the keyword to search the database table to read the records and pass the record which has been encapsulated into object to the micro-grid diagnosis sub-module. The paper raises three delay levels, by adding time delay to achieve the priority of the corresponding logic. At last, example and verification show that Fault Diagnosis of Micro-grid based on Timed-Colored Petri Net (T-CPN) is valid.