Objective To explore the difference of Young＇ s modulus in the biceps brachii during muscle relaxation and tension. Methods A total of 141 healthy male volunteers with age range from 16 to 34 years （ mean 22 years old ） were included in the study. A shear-wave elasto-sonography （ AixPlorer model, Supersonic Imagine, Aix en Provence, France） coupled with a linear array transducer array （4-15 MHz） was used. The scanner was set at the SWE mode and then at Q-BOX mode and the ultrasound trans- ducer was placed directly above the biceps brachii belly and carefully aligned with the muscle bundle. The elastic moduli of the biceps brachii were measured during muscle relaxation and tension in all 141 volun- teers. Results The Young＇ s modulus of biceps brachii was 123. 658 ±31. 392 kPa during muscle tension and 45. 658 ± 13. 479 kPa during muscle relaxation, respectively with statistical significance （P = 0.0000）, Conclusion The Young＇ s modulus of the biceps brachii was higher during muscle tension than those during muscle relaxation.