Abstract: Ultrasonic leak testing is an efficient non destructive testing method for locating leak sources in spacecraft and pipe systems, and its sensitivity can be improved by adopting appropriate methods of experiment and signal processing. Two kinds of experiments are carried out to find ways that may improve the leak tesing sensitivity: one is to enhance the effective turbulence intensity in a noncontact method, the other is to switch the threshold frequency band in a contact method. The results show that the two methods can both increase the effective signal intensity, thus enhance the leak tesing sensitivity.