The reflection asymmetric shell model has been applied to describe the octupole deformed bands in neutron-rich even-even 142Ba and odd-N 145Ba nuclei. The alteating parity bands of 142Ba and the simplex s = -i bands of 145Ba are calculated and compared with the available experimental data. The calculated results are in good agreement with the experimental data. The spin and parity assignments of ground-state of 145Ba are discussed.The results show that the present work is a useful attempt to further explore the nuclear reflection asymmetry in neutron rich region.