A new chemical control method has been applied on Mimosa pigra L., one of the most dangerous weeds in the world, to control this species in a safer way with less environmental pollution. NaCl at different concentrations were applied directly on the leaves or secondary leaflets of this plant. The results showed that NaCl caused the browning on Mimosa pigra L. leaves, starting from the tip of the secondary leaflet, spreading to the base. Browning area increased over time after treatment and with the increase of NaCl concentration. The leaflets browning appeared after 24 hours and completely damaged after 2 days of NaCl 30 g/l treatment. NaCl 30 g/l caused the loss of chlorophyll, primary parenchymal cells plasmolysis, stomatal closing, and death after 24 hours. The loss of chlorophyll in chloroplasts appeared firstly at palisade parenchyma tissue and spread to other parenchyma tissue below. This was the original browning caused by NaCl on Mimosa pigra L. leaf.