In the design of port engineering，the calculation of wind force on the ship controls the selection of mooring facilities. The calculated value of wind force on the ship is determined by calculation constant，windage area of the ship above water，velocity of the wind，reduction coefficient of nonuniform wind pressure and correction coefficient of wind pressure height change. To avoid the error of parameter value in port engineering design，we study the theoretical calculation formula of wind force in the code. Through the analysis of five parameters in the formula one by one and combined with design experience，we obtain the precautions for the selection of windage area of ship，deduce the selection standard of reduction coefficient of nonuniform wind pressure and correction coefficient of wind pressure height change，and put forward the estimation formula of the representative ship height above water，so as to provide some references for the revision of relevant parameters in the code and engineering design.