The invention relates to the field of communication, in particular to a data transmission method and device of a 5G system. The data transmission method is used for reducing the load of the system andimproving the processing efficiency, and comprises the steps of: determining a number of data packets to be sent, and determining a threshold value interval corresponding to the current load of the system; then converging the data packets to be sent according to a preset threshold value when determining that the number of the data packets reaches the preset threshold value corresponding to the threshold value interval, and generating a converged data packet; and finally, sending the converged data packet to a receiver, and triggering the receiver to analyze the converged data packet. Thus, the data packets to be sent can be converged into the converged data packet and then sent to the receiver, the message primitive processing number of protocol interlayer interaction is reduced, the header adding process is simplified, the convergence condition is accurately limited, the effectiveness of the processing result is ensured, the load of a system processor is reduced, the processing efficiency is improved, the scheduling frequency is reduced, the operation overhead of the system is reduced, and the resource consumption is reduced.