  In this paper, we study the properties of the pion-photon transition form
factor (TFF), $\gamma\gamma^{\ast} \rightarrow \pi^{0}$, by using the principle
of maximum commonality (PMC) to deal with its perturbative QCD contribution up
to next-to-next-to-leading order (NNLO) QCD corrections. Applying the PMC, we
achieve precise pQCD approximant for the TFF in large $Q^2$-region without
conventional renormalization scale ambiguity. We also discuss the power
suppressed non-valence quark contribution to the TFF, which is important for a
sound prediction in low and intermediate $Q^2$-region, e.g. the non-valence
quark components affect the TFF by about $1\%$ to $23\%$ when $Q^{2}$ changes
down from $40~{\rm GeV^{2}}$ to $4~{\rm GeV^{2}}$. The resultant pion-photon
TFF shows a better agreement with previous Belle data. It is hoped that
previous discrepancies between the experimental measurements and theoretical
predictions could be clarified by the forth-coming precise data on the Belle II
measurements.
