  Twist-3 distribution amplitudes of the pion and kaon are studied in this
paper. We calculate the fist several moments for the twist-3 distribution
amplitudes (\phi_{p,\sigma}^\pi and \phi_{p,\sigma}^K) of the pion and kaon by
applying the QCD sum rules. Our results show that, (i) the first three moments
of \phi_p^K and the first two moments of \phi_p^\pi and \phi_\sigma^{\pi,K} of
the pion and kaon can be obtained with 30% uncertainty; (ii) the fourth moment
of the \phi_p^\pi and the second moment of the \phi_\sigma^K can be obtained
when the uncertainty are relaxed to 35%; (iii) the fourth moment of the
\phi_\sigma^\pi can be obtained only when the uncertainty are relaxed to 40%;
(iv) we have m_{0\pi}^p=1.10\pm 0.08 {\rm GeV} and m_{0K}^p=1.25\pm 0.15 {\rm
GeV} after including the \alpha_s-corrections to the perturbative part. These
moments will be helpful for constructing the twist-3 wave functions of the pion
and kaon.
