Soy protein bar model system was normally multicompo-nent and thermodynamically unstable and its hardness was increased significantly in the early stage of storage. Xanthan gum is a kind of hydrocolloid with high viscosity and water holding capacity, and it is widely used in food industry as quality improver. This study aimed to evaluate the influence of xanthan gam on texture of soy protein bar model system. The changes in texture, microstructure and T₂ relaxation time of soy protein bar model systems with or without xanthan gum were observed through texture analyzer, confocal laser scanning microscopy (CLSM), scanning electronic microscopy (SEM) and low-field nuclear magnetic resonance (LF-NMR) respectively. Comparing to the samples without xanthan gum, samples with xanthan gum had apparently lower hardness. Moreover, the microstructure was significantly changed by adding xanthan gum, and a higher ratio of small molecules such as water and polyols remained relatively high mobility.