The invention provides a design method for the tube distance of a shell and tube heat exchanger. A division device is arranged in each heat exchange tube and is of a flaky structure. The flaky structures are arranged on the cross sections of the heat exchange tubes. The tube distance of the heat exchange tubes is designed by adopting an optimization method. The design method for the tube distanceof the heat exchanger with the partition devices of new structures is provided, and shock absorption and noise reduction are optimized under the condition of preferentially meeting normal flowing resistance.