The present invention provides pyrroloquinoline quinone lithium salt crystal and a preparation method and application thereof. Characteristic absorption peaks appear when the diffraction angles are 6.222 ± 0.2°, 7.379 ± 0.2°, 7.941 ± 0.2°, 23.631 ± 0.2°, 24.044 ± 0.2°, 25.497 ± 0.2°, 27.541 ± 0.2°, 30.736 ± 0.2°, and 32.306 ± 0.2° degrees in a powder X-ray diffraction pattern of the pyrroloquinoline quinine lithium salt crystal. The maximum value of thermal absorption of the pyrroloquinoline quinine lithium salt crystal appears between 90°C and 96°C through differential scanning calorimetry. Peaks appear when infrared spectroscopy of the pyrroloquinoline quinine lithium salt crystal is at 3396.03 cm -1 , 1652.70 cm -1 , 1604.48 cm -1 , 1500.35 cm -1 , 1355.71 cm -1 , 1243.86 cm -1 , 1147.44 cm -1 , 808.03 cm -1 , 761.74 cm -1 , and 570.83 cm -1 . The pyrroloquinoline quinine lithium salt polymorphism can be applied to preparation of medicines for curing memory damage.
