Abstract: To prepare excellent radiation protection material, bismuth tungstate nanocrystals were synthesized by hydrothermal method, and polyurethane based bismuth tungstate composites were prepared. The effects of crystal structure and morphology on the gamma ray shielding properties of bismuth tungstate were studied. The results indicated that the pH value of precursor solution had a large effect on the synthesis of bismuth tungstate, orthorhombic Bi₂WO₆ were obtained under acidic and neutral conditions, and tetragonal Bi_0.875W_0.125O_1.6875 were obtained under strong alkali condition. With the increase of pH value, the morphology of bismuth tungstate changed from flower like microspheres to persimmon like microstructures, and then to randomly stacked nanosheets. It was found that orthorhombic persimmon-like Bi₂WO₆ showed higher shielding properties to 81 keV gamma rays, whereas tetragonal Bi_0.875W_0.125O_1.6875 showed higher shielding properties to 59.5 and 121.8 keV gamma rays, obvious differences were observed between the mechanical properties of the composites prepared by different crystalline bismuth tungstate. The results of this study provide a reference for the development of new radiation shielding materials with non-toxic, light weight and high efficiency.