Pore collapse, which dominates shock-initiation hotspots, is a long-standing and unresolved issue in detonation physics and energetic materials. In this paper, we proposed the X-ray picosecond tracking imaging for accurately observing the pore collapse of explosives, and presented the dynamic multiple images of pore collapse at meso scales observed in our experiments at the time and space resolutions of 80 ps and 10 m. Important characteristics of pore collapse, such as morphology, velocity, and density, were acquired. This study provides new insights and novel methods for a deeper understanding of the hotspot mechanism and its fine characterization.