Abstract: A scheme of planar location of AE testing was proposed to the structural characteristics of an annular blowout preventer. The preparation work before testing was described. With using twice loading, contrasting the data collected in the two tests, combining the principle of Kaiser effect, and comprehensively analyzing noise sources in the tests, it was assured that the effective signals should be picked up from the data acquired at the pressure holding stage, and the nature of defect should be determined on the basis of them. Finally, it presented the results of test and put forward the problems which urgently needed to be solved in present and the direction of work.