A study is given to the necessary conditions for construction of normal vector wave functions in homogeneous stratified media. The result shows, if normal vector wave functions in a foresaid media need to be constructed, the Morse Feshbach creteria must be observed, and the unit vector of coordinate axis in line with step varying direction of refractive index can be selected as the piloting vector.In some special case,the selective conditions of the piloting vector can be relaxed,only the Morse Feshbach criteria must be observed.