Abstract: Based on the successful application of tissue cultured seedlings of Didymodon tectorum, three physiological indexes, including POD vitality, MDA and chlorophyll content were determined to check out the influences of the rare earth elements stress under gradient concentrations treatment. We choosed the light rare earth La³⁺, Ce⁴⁺ and heavy rare earth Y³⁺ three elements and setted respectively six concentrations under the single elemnet stress, in order to explore the physiological response and changes of D.tectorum to the rare earth stress. The results were the following:(1)The peroxidase(POD) activity and malondialdehyde(MDA) content in D.tectorum were lower in each treatment group than those in the control group; Ce⁴⁺ element significantly promoted the POD activity at 3.55×10^-2 mmol·L^-1, at 7.1×10^-2 mmol·L^-1, the content of MDA increased. It showed that the D.tectorum had a stronger response to Ce⁴⁺ stress, while La³⁺ showed a more gradual change in POD activity, and the stress response was weaker; Y³⁺ treatment was intermediate; (2)At lower concentrations of La³⁺(1.8×10^-2 mmol·L^-1) and Ce⁴⁺(3.55×10^-2 mmol·L^-1) the contents of chlorophyll a, chlorophyll b and total chlorophyll increased significantly, but at higher concentrations of all three rare earth elements, the contents of chlorophyll decreased obviousily. This study laid the foundation for further exploration of the effects of rare earth elements on the growth and the development of bryophytes in the Baiyun obo rare earth mineral area.