Experiment was conducted with subculture plantlets of M7, Malus micromalus Mak., and SH15 (Ralls Janet ×M. honanensis Rehd.), the injury caused by 0.6% NaCl between subculture plantlets and rooting plantlets were counted. Results showed the critical concentration of NaCl ranged from 0. 6% to 0. 8%. The injury index, relative regeneration coefficient, relative biological yield, free Pro content and cell membrane permeability had some correlation with the tolerance of the rootstock.The salt tolerance of subcu...