Abstract: The shortcomings of the experimental teaching device for boiling/condensation heat transfer on single tube are analyzed. When the water-side water flow of the experimental section is low, it is found that the large fluctuation of water temperature at the outlet of the water side is the main factor causing inaccurate experimental results and low experimental operation efficiency. By using the large-flow bypass method, the water-side temperature of the experimental section can be kept stably so that the margin of experimental data error can be controlled within ±20%, and the experiment wait time can be shortened which improves the experimental teaching efficiency.