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.
