Molecular dynamics simulations were used to investigate the effects of a series of vacancy defect concentrations （0%， 1.56%， 6.25% and 12.5%） on the sensitivities， mechanical properties and bursting properties of dihydroxylammonium 5，5"-bistetrazole-1，1"-diolate （TKX-50）. Firstly， perfect crystal model and vacancy defect models were first constructed， and the correctness and validity of the Dreiding force field used in the study were verified. Then the models were geometrically optimized and molecular dynamics simulated， and the trajectory files to reach thermodynamic equilibrium were statistically and analytically analyzed. It was found that vacancy defects lead to decreases in the cohesion energy density and in the number of total hydrogen bonds of TKX-50， indicating that TKX-50 containing vacancy defects has increased susceptibility and decreased safety. And with the increase of vacancy defects， the number of hydrogen bonds between hydroxylamine cations remains almost constant， and the number of hydrogen bonds whose hydrogen bond acceptor is oxygen atom on bitetrazolium anion is significantly reduced compared with other hydrogen bonds. Besides， the vacancy defects reduce the bulk modulus （K）， elastic modulus （E）， and shear modulus （G） of TKX-50 by 1.530-4.122 GPa， 3.066-10.652 GPa， 1.216-4.202 GPa， respectively. It indicates that the stiffness of TKX-50 crystal decreases with the increase of vacancy defect concentration. The positive Cauchy pressure （C₁₂-C₄₄） of all models indicates that all models exhibit ductility， and the values of K/G and Poisson"s ratio （γ） increase with the increase of vacancy defect concentration， indicating that the toughness and plasticity of TKX-50 are enhanced by the increase of vacancy defects. In addition， the vacancy defects also reduce the detonation velocity and detonation pressure of TKX-50 by 93-317 m·s^-1 and 1.0~3.5 GPa， respectively， indicating that the damage power of defect crystals is reduced.