【Objective】To probe the role of ethylene in asparagus bean [Vigna unquiculata W. ssp. sesquipedalis (L.) Verd] response to phosphorus-deficiency stress. 【Method】Changes of ethylene emission in seedlings of 3 asparagus bean cultivars differing in tolerance to phosphorus-deficiency were studied in 2 treatments (+P and -P) in soilless-culture experiment. 【Result】Ethylene emission in asparagus bean seedling increased under P-deficiency stress. The increase of ethylene emission in root of cv. Luhuabai (high P-deficiency-tolerance) > cv. Xianggangqing (middle P-deficiency-tolerance) >cv. Erlubai (low P-deficiency-tolerance). The increase of ethylene emission in older leaf and stem of cv. Erlubai>cv. Xianggangqing> cv. Luhuabai. The increase of ethylene emission in youngest fully-expanded leaf of cv. Luhuabai >cv. Erlubai>cv. Xianggangqing. There was a little increase of ethylene emission in younger leaf and stem. 【Conclusion】The results indicated that the increase of ethylene emission in asparagus bean root and older stem and leaf might induced morphological changes in root and stem under phosphorus deficiency stress, then enhanced the ability of phosphorus acquisition and free radical scavenging in root, enhanced translocation of nutrient and water, thus enhanced the adaptability of asparagus bean seedlings to phosphorus deficiency stress .