Information on the catalytic mechanism is crucial for understanding heterogeneous catalysis of glycerol hydrogenolysis. In this work, we proposed a simple and effective method to study the catalytic mechanism of glycerol hydrogenolysis with Cu/Mg–Al mixed-oxide as catalyst. This method is based on the memory effect of the hydrotalcite-derived Mg–Al mixed-oxide and the tunable property of hydrotalcite interlayer distance. The experimental results showed that the basal spacing of hydrotalcite could work as an effective tool to reflect the relationship between desorption of products and reaction conditions. With this tool, the effect of H2 pressure on glycerol hydrogenolysis was elucidated. It was found that H2 pressure affected desorption and yield of products.