The condition of generator-transformer system in electrical tests during integrated starting is different from that in normal operation. The characteristics of different test stages were discussed based on the electrical test process in integrated starting of practical generating units. Aimed to the problems occurred in integrated starting process, some relay protection strategies were suggested for electric start-up, such as fixed value setting basis of temporary power supply of excitation transformer, adjustment principle of setting value used for generator synchronization, protection switching principle. These strategies will provide references for the integrated starting of large generating units.