The present disclosure provides an earthquake and tsunami warning system and a transmission method for a primary notification message thereof. The transmission method includes: a base station pages all terminals via a paging message containing indication information of an earthquake and tsunami warning system (ETWS) message, and transmits security information of an ETWS primary notification message via the resource prearranged with the terminals, and basic information of the ETWS primary notification message is transmitted within the paging message or via the prearranged resource; the terminals receive the security information of the ETWS primary notification message via the prearranged resource after receiving the paging message containing indication information of the ETWS message, and obtains the basic information of the ETWS primary notification message from the paging message or receives the basic information of the ETWS primary notification message via the prearranged resource. The technical solution provided by the present disclosure can achieve the transmission of the ETWS primary notification message as well as meet the time delay requirement, and modify the base station and terminals slightly with little or no overhead increasing.