Abstract: 2000 and 2002 "South China Sea Air-Sea Flux Measurement" project are the extension of Xisha tower air-sea flux measurement which include in the South China Sea Monsoon Experiment (SCSMEX) program developed over the South China Sea (SCS) in 1998. In this paper, firstly, the bulk transfer coefficients variation feature with wind speed in unstable stratification was calculated and analyzed by means of these two air-sea flux gradient measurement data before and after SCS monsoon onset. Research showed, in general, that the bulk transfer coefficients corresponded well with wind speed especially in high speed stage, but there was a little dispersion in low speed stage. The further study found that the main reason causing dispersion had relation to stratification stability and air-sea temperature difference could be used to replace the stratification stability. Based on above results, the bulk transfer coefficients calculation formula being adapted to the unstability stratification atmosphere over SCS was constructed and tested. Secondly, some representative similar calculation formula of the bulk transfer coefficients, including Yan's results developed from 1998 SCSMEX data at same place and Kara's and Xu's results developed by means of west Pacific Ocean data, was chosen to compare with the formula in this paper on the basis of the model results calculated by these two observation.