Abstract: In this contribution,the formulae of the scalar roughness Zt,Zq,similar to the wind speed roughness Z0 overa smooth sea surface,are introduced in detail,and extending the Monin-Obukhov similarity theory to smooth surface.Stratification modified profiles of wind,temperature and humidity over smooth surface are obtained in uniform with the profiles overa rough one.Reasonability of the theory is also discussed.The model is applicated in the computation of the gradient data observed in three differentsea areas.It's resulted that the effect of stratification on the air-sea flux through a smooth sea surface and on the bulk transfer coefficients under light wind are much stronger than the effect of wind speed.The formulas of the bulk coefficients variation with wind and stability is presented.