The present invention provides a data transmission device and method thereof. A data transmission system includes: an electric device generating an input message; a Natural Language Processing (NLP) engine connected to the electric device, receiving the input message, and judging whether an output message corresponding to the input message is available on a real-time basis or on a non-real-time basis; a plurality of third-party servers; a service cloud framework connected to one of the NLP engine, the electric device, and the plurality of third-party servers to obtain a real-time information; and a buffer cloud framework connected to one of the NLP engine, the electric device and the plurality of third-party servers, proactively downloading at least one updated data from the plurality of third-party servers once in a predetermined period of time, automatically saving the at least one updated data therein, and obtaining a non-real-time information therefrom.