[en] The low-energy and high-energy behavior of the pion.photon transition form factor F_π_γ(Q"2) are sensitive to the transverse and longitudinal distributions of the pion wave function, respectively.Acareful study of F_π_γ(Q"2) shall thus provide helpful constraints on the properties of the pion wave function. In this paper, we present a combined analysis of the data on F_π_γ(Q"2) reported by the CELLO, the CLEO, the BABAR, and the BELLE Collaborations. It is performed by using the method of least squares. By using the combined measurements of the BELLE and CLEO Collaborations, the pion wave function longitudinal and transverse behavior can be fixed to a certain degree, i.e. we obtain β element of [0.691, 0.757] GeV and B element of [0.00, 0.235] for P_χ_"2 ≥ 90 %, where β and B are two parameters of a convenient pion wave function model. It is noted that the distribution amplitude of such a pion wave function can mimic various longitudinal behaviors, as suggested in the literature under a proper choice of parameters. We observe that the CELLO, CLEO, and BELLE data are consistent with each other, all of which prefer the asymptotic-like distribution amplitude; while the BABAR data prefers a more broad distribution amplitude, such as the CZ-like one. (orig.)