Chemical components and relative contents of essential oil from fresh flowers of three tropical water lily were identified and analyzed by using GC-MS. The results show that 25， 23， and 25 compounds are identified in essential oil from fresh flowers of cultivar ‘Ruby’ and ‘Daubeniana’， and Nymphaea caerulea Savigny， respectively； there are eight identical components， in which， the relative content of 8-hexadecyne is the highest （above 30.00％）. Alkyne， alkane， alkene， alcohol， and ketone compounds are the dominant component， in which， relative contents of alkyne compounds are the highest in essential oil from fresh flowers of cultivar ‘Ruby’ and N. caerulea （33.62％ and 37.28％， respectively）， while that of alkane compounds is the highest in cultivar ‘Daubeniana’ （33.91％）.