We study the sin2 phi azimuthal asymmetry in the pi N Drell-Yan process, when the nucleon is longitudinally polarized. The asymmetry is contributed by the combination of the Boer-Mulders function and the longitudinal transversity distribution function. We consider the Drell-Yan processes by pi(+/-) beams colliding on the proton and deuteron targets, respectively. We calculate the sin2 phi azimuthal asymmetries in these processes using the Boer-Mulders function and the longitudinal transversity from spectator models. We show that the study on single polarized pi N Drell-Yan processes can not only give the information on the new three-dimensional parton distribution functions in momentum space but also shed light on the chiral-odd structure of the longitudinally polarized nucleon.