Abstract: This study examined the effects of NaCl stress on the activity and expression of plasma membrane H+-ATPase in roots and leaves of Broussonetia papyrifera. Results showed that plasma membrane H+-ATPase activity of B. papyrifera plantlets increased under salt stress. In roots, the activity was elevated as NaCl concentration increased, while in leaves, it increased at low NaCl concentration and then decreased at high one. Laser confocal microscopy and Western blot analysis demonstrated that the expression of plasma membrane H+-ATPase increased in response to NaCl stress. The elevated protein level of plasma membrane H+ATPase might play a role in the increase of its activity under NaCl stress.