Gas transfer velocity (k) is a factor driving Greenhouse gases exchange between water-air interface. But the estimate of k showed great uncertainly. To explore the control factors and variation of k, and select suitable k estimate model in large lake, three different parameterized equations were chosen for estimating k in Lake Taihu. Results indicated that velocity scales for wind shear and convection (u^* and w^*, respectively) showed diurnal cycle with high values during nighttime and low values during day, which were two important parameters in k estimate. As a result, k showed similar variation. In the large lake, the k was mainly dominated by wind shear, and wind speed was useful for estimating k. The annual mean value of k ranged from 1.27 to 1.46 m/d in Lake Taihu. Because of the spatial heterogeneity, the parameterized models in single site maybe not suitable for estimating k in other lakes. However, the lake area may be useful predictor for k.