Purpose Heavy metal pollution in the environment may affect plant growth. Exploring remediation agents that alleviate cadmium toxicity in plants is the research hot spots in the field of cadmium pollution remediation agent around the world. Methods The ryegrass culture variety "Dongmu 70" was used as the test material, based on Hoagland nutrient solution, the experiment set normal nutrient solution（CK）, normal nutrient solution+100 mg·L-1CDs（CDs）, 100 mol·L-1 Cd stress nutrient solution（Cd）, Cd+50 mg·L-1CDs（T1）, Cd +100 mg·L-1 CDs（T2）, Cd +150 mg·L-1 CDs（T3）. There were 6 treatments. To study the effects of CDs on the physiological characteristics of ryegrass treated for 18 days under cadmium stress. Results The results showed that cadmium stress severely inhibited the growth of ryegrass. The application of CDs could effectively alleviate the cadmium stress of ryegrass. Compared with the Cd treatment, the plant height, fresh weight, dry weight and root activity of T2 were increased by 54.89%, 117.3%, 116.67% and 58% respectively, the total chlorophyll content of T2 was increased by 68.1%, the activities of SOD, POD and CAT increased significantly, Cd accumulation in leaves and roots of T2 was decreased by 22.92% and 34.74% respectively, CDs could effectively adsorb Cd2+ and reduce its entry into ryegrass. Under the experimental conditions, the mitigation effect of CDs on Cd stress increased with the increase of CDs concentration. The repair effect of 100 mg·L-1 CDs on cadmium toxicity caused by 100 mol·L-1 Cd2+ is the best. The repair effect did not increase significantly with the increase of concentration, and even there will be inhibitory effect. Conclusion Application of CDS could promote the growth of ryegrass under cadmium stress, improve the content of photosynthetic pigment and the activity of antioxidant enzymes in ryegrass, remove excess reactive oxygen species, and inhibit the absorption of cadmium by ryegrass，effectively alleviate the cadmium stress of ryegrass. This study can provide a basis for the application of CDs as a new cadmium pollution remediation agent in soil remediation.