  We present the first lattice-QCD calculation of the kaon distribution
amplitude using the large-momentum effective theory (LaMET) approach. The
momentum-smearing technique has been implemented to improve signals at large
meson momenta. We subtract the power divergence due to Wilson line to high
precision using multiple lattice spacings. The kaon structure clearly shows an
asymmetry of the distribution amplitude around $x=1/2$, a clear sign of its
skewness. We also study the leading SU(3) flavor symmetry breaking relations
for the pion, kaon and eta meson distribution amplitudes, and the results are
consistent with the prediction from chiral perturbation theory.
