Abstract: It is very important for every wind wave forecasting formula to deal correctly with the effects of early days wind before the coming of this wind wave.So this is a research problem with great value and great attention is paid by the scholars of every country scholars of every country.On the basis of logical inference,in accordance with two states of wind wave growth,this paper proposes a functional relation formula H(U,T'_e)=H(U,F'_e) In order to enable this formula to satisfy the equivalent condition of the quivalent wind time and the equivalent wind field,the recursive estimation method is utilized.Consequently the precision of wind wave forecasting is manifested due to the full consideration of the effects of early days wind wave.