Starting with the transition amplitude of a photon to the vacuum through the non-local quark-antiquark current

the light-cone photon wave function gγ3（u

P2） is singled out from the Lorentz decomposition.Its analytic expression is obtained in the framework of the quantum chromodynamics（QCD） low-energy effective theory

and its behavior and trend with respect to the fraction（u） of the quark momentum are analyzed.The coupling constant

Gγ（P2）

of the quark-antiquark vector current to the virtual photon state is also obtained.The wave functions corresponding to different virtuality are symmetric with the transformation u → u（u=1-u） and they are not zero at the end points u=0 and u=1.The real photon wave function according to P2=0 has no physical meaning

since the coupling constant Gγ（P2） vanishes at P2=0 which guarantees that the non-local vector quark current is decoupled from the wave function.