The utility model provides a photovoltaic power generation system relaying protection system that is incorporated into power networks, including photovoltaic power generation system and traditional electric wire netting, it has current quick breaking protection unit and directionality current protection unit to connect in parallel between photovoltaic power generation system's the output and the input of traditional electric wire netting, the current quick breaking protection unit includes the connection bus, establishes first circuit breaker and second circuit breaker on the connection bus, directionality current protection unit includes that fusing protector and the voltage transformer of series connection, switch circuit breaker and current transformer, the the?direction?of?current flow of series connection judge component, electric current metering device and electric energy metering device, electric current metering device and the?direction?of?current flow judge that the component concerns for the logic AND. The utility model discloses can make the distribution network behind the photovoltaic power generation system plain net have the function of current quick breaking protection and the protection of directionality electric current to guarantee whole power grid operation's security and reliability.