The interface effect is one of the most important factors that strongly affect the structural transformations and the properties of nano-/submicro-crystals under pressure. However, characterization of the granular boundary changes in materials is always challenging. Here, using tetrakaidecahedral Zn 2 SnO 4 microcrystals as an example, we employed alternating current impedance, X-ray diffraction methods and transmission electron microscopy to elucidate the effect of the interface on the structure and electrical transport behavior of the Zn 2 SnO 4 material under pressure. We clearly show that grain refinement of the initial microcrystals into nanocrystals (approximately 5a €‰nm) occurs at above 12.5a €‰GPa and is characterized by an anomalous resistance variation without a structural phase transition. A new phase transition pathway from the cubic to hexagonal structure occurs at approximately 29.8a €‰GPa in Zn 2 SnO 4. The unexpected grain refinement may explain the new structural transition in Zn 2 SnO 4, which is different from the previous theoretical prediction. Our results provide new insights into the link between the structural transition, interface changes and electrical transport properties of Zn 2 SnO 4.