Abstract: Abstract The indomethacin-nicotinamide cocrystal was prepared by hot melt extrusion(HME)to improve the dissolution of indomethacin in vitro. The optimum preparation conditions were investigated using temperature and rotate speed as variables. Thermogravimetric analysis(TGA), determination of content and determination of related substances were performed to evaluate the thermal stability of indomethacin during the process. Cocrystal was also prepared by solution crystallization from acetonitrile. The products obtained by the two methods were characterized by differential scanning calorimetry(DSC), Fourier transform infrared(FTIR)and powder X-ray diffraction(PXRD). The solubility and dissolution advantages of cocrystal were evaluated. The results showed that the HME method could successfully prepare the indomethacin-nicotinamide cocrystal at 115 °C and eutectic mixture was formed during the process. The cocrystal significantly improved the solubility and dissolution of indomethacin in deionized water, with pH 5. 5 and pH 6. 8 phosphate buffer. The preparation of poorly soluble drug cocrystal by HME can significantly improve its solubility, providing new idea for the development of poorly soluble drugs and HME technology.