Abstract: At present, the most widely applied method for offshore platform detection is active detection method, such as ultrasonic testing, but the working conditions will have impact on it. The passive detection, such as acoustic emission(AE), avoid this problem, the on-line detection to the offshore platform is realized. Description was made of the results of transient wave, stress wave, guide wave and modal acoustic emission for the tube testing based on wave motion theory. The detection to the complex structure based on wave motion theory was expected.