4-Dimethylamino-N-methyl 4-Stilbazolium Tosylate（DAST） crystals were prepared by the slope nucleation method. The Vickers hardness of DAST crystal was studied on (001) and (110) faces. It was found that the Vickers hardness increases with increasing load and the Hv on (001) face is higher than that on (110) face. The values of Meyer’s index number n and hardness were calculated from Hv. The results showed that the DAST crystals belong to the soft material category.