The ruptures of RDX crystalline particles in ensembles and mesoscale fracture behaviors of bulk single crystal are presented in this work. First, the particles ruptures of 3 types RDX ensembles subjected to quasi-static compression were investigated. The rupture ratio was defined to describe the coherence strength of crystalline particles. The rupture ration of commercial coarse RDX lot is 1.57 which is much higher than that of re-crystallized lot with 1.47 and, the spheroidized RDX lot bears the minimum ration of 1.17 which shows the highest resistance to rupture. In the case of the nanoindentation of a bulk single RDX crystal, the regular pop in events on face (210) were reported in this work. Through the nanoindention tests, the yield stress or fracture initiation stress of RDX was obtained as 465 MPa, which is far below the hardness of 550 MPa. The mean fluctuation stress on the loading/unloading curve is calculated as approximately 8 MPa and the corresponding indentation depth on the (210) face is 1 micrometer and the implication of the depth is discussed.