Abstract: To explore the wheat tolerance to cadmium toxicity and mechanism of cadmium stress during wheat seed germination and seedling growth period, Shangmai 156 was used to evaluate the effects of cadmium stesss on seed germination, seedling growth, osmotic adjusting materials and protective enzyme system of wheat, using soilless cultivation tests of different concentrations of cadmium stress (0, 0.04, 0.4, 0.8, 1.2 mmol?L_-1).The results showed that the low concentration of cadmium (less than 0.04 mmol?L_-1) was no obvious inhibitory effect on seed germination and seedling growth of wheat, while high concentrations of cadmium (0.4 mmol?L_-1) had significant inhibitory effects on above indicators, and within the scope of the germination rate, germination potential, germination index, vigor index, plant height, root length, shoot fresh and dry weight and root fresh and dry weight decreased with the increase of cadmium concentration. The content of soluble sugar in leaves decreased at a slightly higher level, and was the largest at 0.04 mmol?L_-1, and increased by 6.99% compared with the control. The change rule of free amino acids, protein and MDA content was similar. All of them increased with the increase of cadmium stress, and the maximum was 0.4 mmol?L_-1 of cadmium, which was 2.61, 5.20 and 7.99 times of thecontrol, respectively. The activity of SOD, POD and CAT in wheat leaves was the highest when the concentration of cadmium was 0.4 mmol?L_-1, which was increased by 49.32%, 85.34% and 40.59% compared with the control,and the difference was very significant (p<0.01) with the control (p<0.01); The activity of Cd decreased, while the concentration of Cd continues to increase. With concentration of Cd2+ 0.04 mmol.L-1, the APX acativity were heighest, and then decreased with increasing concentration of Cd2+.