  We have performed a systematical calculation of the pion ($\pi, K, \eta$) and
heavy pseudoscalar meson S-wave scattering lengths up to ${\cal O}(p^3)$ in the
chiral perturbation theory in the heavy quark symmetry limit. With the three
scattering lengths from the lattice simulations as input we estimate the
unknown low-energy constants. Then we predict all the other unmeasured
scattering lengths. The analytical expressions and predictions may be helpful
to future investigations. Especially we note that the DK scattering length is
positive. Therefore their interaction is attractive, which helps to lower the
mass of the "bare" charm-strange scalar state in the quark model through the
couple-channel effect.
