The present invention relates to a new type of eutectic crystal of lorcaserin hydrochloride and benzoic acid, when compared with the prior art, the eutectic crystal has the improved properties of good stability, low solubility, and being suitable for the application of controlled-release preparation the present invention also relates to a method for preparing the eutectic crystal, a pharmaceutical composition thereof and the use thereof in the manufacture of drugs for treating and/or preventing diseases associated with 5HT2C.
