Abstract: The water spray system is the main fire extinguishing method in the transformer area of nuclear power plants. However, in recent years, there have been multiple cases of false spraying caused by the misoperation of the rain valve. This paper discusses and studies the design basis and engineering status of the water spray self-starting logic of the fire alarm system, and proposes an effective logic design scheme, which is helpful for optimizing the self-starting logic of subsequent engineering projects, Reduce the risk of misoperation.