The 2 gas transfer velocity (2 ) at air-sea interface is usually parameterized with the wind speed, but to a great extent is defined by waves and wave breaking. To investigate the direct relationship between 2 and waves, laboratory experiments are conducted in a wind-wave flume. Three kind of waves are forced in the flume: monochromatic waves generated by a wavemaker, mechanically-generated monochromatic waves with superimposed wind forcing, and pure wind waves with 10-meter wind speed ranging from 4.5 m/s to 15.5 m/s. The wave parameters are found to be well correlated with 2 while wind speed alone can not adequately describe 2 . To reconcile the data sets, non-dimensional empirical formulae are established in which 2 is expressed as a function of wave parameters as the dominant term and an enhancement factor to account for additional influence of the wind.