From the nuclear Schrdinger equation of a diatomic molecule with the vibration rotational interaction term,we derive a wave function which is related not only with vibrational quantum number,but also with rotational one.The Franck Condon factors of the two band systems A1Π→X1Σ+ and b3Σ+→a3Π of BF are calculated by use of the derived wave function with the rotational quantum number ranging from J=0 to J=200.The results obtained can be used in the cases under low or high temperature condition,and also that under the condition of strong shock wave.