Using the first principle calculation based on the density functional theory, we systematically investigate the stabilities and the structural and electronic structures of fully hydrogenated and fully fluorinated SbAs and BiSb. The results show that the SbAs and BiSb transform the buckled structure into quasi-planar structure after being fully hydrogenated or low-buckled structure after being fully fluorinated. Stability studies show that both the SbAs and BiSb structures（intrinsic, full hydrogenated, and fully fluorinated) are highly stable, and thus likely to be obtained in experiment. The electronic structure study shows that both SbAs and BiSb turn from wide band gap semiconductors into narrow direct-gap semiconductors after being fully hydrogenated and fully fluorinated, meanwhile the band structures still have good linear dispersion. Based on further analyses of the electronic structures of quasi-planar or low-buckled SbAs and BiSb, the reasons for the changes of band structures are revealed. Calculations show that the fX-SbAs（X=H, F) films on h-BN substrate can maintain the direct band gap characteristics because of the weak coupling between them, indicating that they may have great applications in the field of optoelectronic devices in the future.