Mechanical characterization of human red blood cells (RBC) is crucial to the study of the pathology, drug screening, clinical diagnosis, and treatment of Parkinson’s disease. Oxidative stress has been found to be a dominant factor among the causes of Parkinson’s disease. This paper proposes a method for measuring cell mechanical properties using optical tweezers. By measuring the membrane shear modulus of RBCs treated with hydrogen peroxide (H2O2) at different concentrations, mechanical properties of RBCs under oxidative stress were analyzed. The experimental results reveal that increased membrane shear modulus and decreased cell deformability are commensurate with increasing concentrations of H2O2. This proposal will benefit both basic research and clinical applications in the field of Parkinson’s disease research. The results will also provide a guideline for measuring the mechanical properties of other cells.