Abstract: This invention belongs to the modern pharmaceutical field of Traditional Chinese Medicine, and relates to an herbal extract of Chinese Motherwort and its application in pharmacy, which specifically relates to the crystal structure of a Chinese Motherwort extract: Leonurine, and its application in the preparation of medicine. The chemical name of the above-mentioned Leonurine is 4-guanidino-1-)butyl 4-hydroxy-3,5-dimethoxybenzoate. The invention by specific methods prepares leonurine as 6 kinds of crystals with different crystal forms. Specifically, there are six different structures of leonurine sulfate crystals, two of them are hydrate, two are anhydrous crystal form, one is methanol solvate, one is ethanol solvate. The leonurine crystal forms of this invention can applicate in preparing medicine such as insulin sensitizer, hypoglycemic and lipid-lowering drugs.