The effects of cold rolling reduction 20%~90% on the phase structure, microstructure, crystal orientation, mechanical properties and Young’s modulus of a low modulus biomedical b titanium alloy were investigated by tensile tests and XRD, EBSD and TEM. The changes of the microstructure and mechanical behavior of the deformed titanium alloy were described. The formation of nanocrystallines in the deformation bands of b titanium alloy with BCC crystal structure during cold rolling was analyzed and a new viewpoint that nanostructure and texture jointly influence the Young’s modulus of b titanium alloy was suggested.