Pharmaceutical cocrystal,as a new solid modification,has attracted more and more attention,which can improve the solubility and bioavailability of oral drugs.Ibuprofen is classified as a biopharmaceutical classification system class Ⅱ drug with high permeability but low solubility.The main task of this paper was to improve the physicochemical properties of IBU by designing and systhesizing cocrystals.Ibuprofenisonicotinamide was prepared by solvent evaporation method combined with ultrasound technology.Solid state characterization by powder X-ray diffraction,differential scanning calorimetry,thermogravimetric analysis and fourier transform infrared spectroscopy showed that a new crystalline phase was successfully formed.Single-crystal X-ray diffraction results showed that hydrogen bonds were formed between ibuprofen and isonicotinamide with the molar ratio of 1∶1.The aqueous solubility results showed that the formation of cocrystal increased the solubility twice while did not affect the stability of ibuprofen in simulated gastric fluid.In addition,melting point and bond length theory were used to analyze the product and judged that the product is cocrystal rather than salt.