To improve the reliability of a diamond type distribution network, a new self-healing strategy for a secondary protection system is introduced. First, substation outlets and bus sections in switch stations are equipped with different kinds of self-healing terminals, which include line optical differential, simple bus difference and branch line overcurrent protections. The communication mode is optical fiber hand-in-hand connection. Thus accurate fault location and rapid isolation are achieved. Then, the self-healing control of the connective switches in the ring is instituted, supplemented by automatic device transfer between stations. The load in the non-fault section can be recharged rapidly when a single normal or maintenance fault, or double normal faults occur. The simulation results show that the fault can be located and isolated in the minimum range and the non-fault section load recovered within 0.5s, thereby meeting reliability requirements. This work is supported by the Science and Technology Project of the Headquarters of State Grid Corporation of China (No. 52094020000Y).