Based on the in situ measurements obtained by the Bohe observation platform in the South China Sea from February 1 to May 21, 2016, heat flux at sea surface is calculated with bulk-aerodynamic method, and that in droplet evaporation layer is then estimated with eddy covariance method. By comparing the fluxes at sea surface and in droplet evaporation layer, we found that significant difference exists between them, and sea spray is responsible for it. It is also found that the heat flux caused by sea spray is positively correlated with wind speed when the wind speed is medium and low. From the point view of sea spray formation mechanism, latent heat flux changes are more obvious than sensible heat flux changes at same wind speeds.