The invention provides a dual-mode communication networking method and system based on a media access control layer. The method comprises the steps of obtaining to-be-sent business data, and framing the to-be-sent business data to generate data frames; storing the data frames to sending data linked lists which correspond to business types, according to the business types of the to-be-sent businessdata; obtaining a data sending task set by a user, and obtaining current to-be-sent data frames from the sending data linked lists according to business priorities in the task; determining communication networking modes of the current to-be-sent data frames according to the business types; packaging the current to-be-sent data frames into data packets according to bearable frame lengths corresponding to the communication networking modes, and generating packaging information; and sending the data packets and the packaging information. The dual-mode communication networking is realized in themedia access control layer, the physical layer difference is shielded, the network access optimum selection is realized, the switching speed is fast, an error switching rate is low, the capacity of awhole communication system is improved, and the data transmission efficiency is improved.