The spatio-temporal characteristics of O₂ in the rhizosphere of Cr hyperaccumulator Leersia hexandra Swartz were studied using pot experiments with soils spiked with different levels (0, 50, and 100 mg/kg) of Cr. The results show the hot spots of O₂are along entire root of L. hexandra, which are relatively higher at the root tips. O₂ concentration in the rhizosphere is significantly higher than that in the bulk soil. For example, O₂ concentration at the center of the root is 1.45 times higher than that 5 mm away from the root center. Besides, radial oxygen loss(ROL) becomes weaker when the distance from the root center becomes farther. During the experimental period of 8 days, O₂ concentration at the root center of L. hexandra in the control group is 77.2%, which is significantly higher than that of 50 mg/kg Cr treatment group (50.2%) and 100 mg/kg Cr treatment group (42.3%). ROL is increased first and then decreased in all the 3 groups, which reaches the highest on the fourth day. ROL is significantly inhibited by the addition of Cr into the soil, which might be the protective behavior of L. hexandra to avoid the oxidation of Cr(III) into more toxic Cr(VI).