To study the detonations waves propagation characteristics of hexanitrostilbene (HNS), the critical thicknesses of HNS with particle size of 20 μm, 9 μm, 89 nm and densities of 1.0,1.570 g·cm^-3 were measured by wedge shaped charge test. Results indicate that the HNS particle size has obvious influence on detonation wave propagation. With the decreasing particle size of HNS, the critical thickness decreases, and the propagation capability of detonation waves increases. Increase of charge density is advantageous to detonation waves propagation. When the charge density of HNS-Ⅳ(89 nm) is 1.570 g·cm^-3, it′s critical thickness is 0.46 mm.