  We investigate the next-to-next-to-leading order (NNLO) QCD radiative
corrections to the pion electromagnetic form factor with large momentum
transfer. We explicitly verify the validity of the collinear factorization to
two-loop order for this observable, and obtain the respective IR-finite
two-loop hard-scattering kernel in the closed form. The NNLO QCD correction
turns to be positive and significant. Incorporating this new ingredient of
correction, we then make a comprehensive comparison between the finest
theoretical predictions and numerous pion form factor measurements in both
space-like and time-like regions. Our phenomenological analysis provides strong
constraint on the second Gegenbauer moment of the pion light-cone distribution
amplitude (LCDA) obtained from recent lattice QCD studies.
