Abstract: In order to enhance the wetting ability of water in the dust prevention pipeline underground,a magnetizer and digital gauss meter were applied to magnetize different water samples. The influence degree and features of external magnetic field on water's surface tension were analyzed under the different magnetic field intensity and magnetized time, and a comparison was conducted between external magnetic field and surfactant. The results showed that under the certain magnetic field parameter s,external magnetic field could reduce water's surface tension,but its influence degree was relatively small. After the water with a high initial surface tension was magnetica lly treated,the average surface tension would be 50 ~ 60 m N 1 m generally,could reduce the original value by 7. 2% - ~ 27. 1%,and with the magnetic field parameters varie d,there would be certain wave variation. Under the low concentration,the surfactant could make the water's surface tension reduced below 50 m N/ m,the best surfactant C ould further reduce the surface tension to 30 ~ 40 m N 1 m and the decreasing range would be 1. 5 ~ 4. 0 times as compared with the magnetized water. External magnetic field could be a green method to change the wetting ability of water,but it should be applied according to site specific requirements and in combination with other features 0 f the magnetized water.