The invention discloses a message reminding method, a system and a device thereof, and belongs to the field of communication. The method comprises the following steps: a charging network element device encapsulates content needing to remind a user into a specified field of preset message, and sends the encapsulated message to a service control network element device; and after receiving the encapsulated message, the service control network element device extracts the content in the specified field, generates reminding message according to the extracted content, and sends the reminding message to a client. The system comprises the charging network element device and the service control network element device. The charging network element device comprises a judging module, an encapsulating module and a sending module. The service control network element device comprises a receiving module, an extracting module, a message generating module and a message sending module. The method, the system and the device achieve the aim of reminding the user, and simultaneously avoid perplexity caused when the prior charging network element device and the prior service control network element device send the reminding message to the user respectively.