In the paper, a novel perovskite microcrystalline with a capsule-free cavity box structure was creatively prepared through solvent thermal reaction, and the composition and structure of CH3NH3PbI3 perovskite microcrystalline were further characterized by scanning electron microscope (SEM) and energy dispersive X-ray (EDX) element mapping. The SEM results show that the grain size of the prepared CH3NH3PbI3 perovskite microcrystalline is more than 100 μm. Furthermore, X-ray diffraction (XRD) analysis was used to characterize the material decomposition of perovskite microcrystals before and after 150 d of air aging. The XRD results indicate the prepared perovskite microcrystalline could be stably preserved in the air for 150 d without degradation. Our method provides technical guidance for further enriching the morphology of CH3NH3PbI3 perovskite microcrystalline.