  We study neutral and charged meson properties in magnetic field. Taking
bosolization method in a two-flavor Nambu--Jona-Lasinio model, we derive
effective meson Lagrangian density with minimal coupling to the magnetic field,
by employing derivative expansion for both the meson fields and Schwinger
phases. We extract from the effective Lagrangian density the meson curvature,
pole and screening masses. As the only Goldstone mode, the neutral pion
controls the thermodynamics of the system and propagates the lang range quark
interaction. The magnetic field breaks down the space symmetry, and the quark
interaction region changes from a sphere in vacuum to a ellipsoid in magnetic
field.
