Abstract: OBJECTIVE To establish a method for the determination of lurasidone hydrochloride and to study the stability of the lurasidone hydrochloride-shikimic acid coamorphous system. METHODS Three kinds of coamorphous lurasidone hydrochloride-shikimic acid with molar ratios of 1:1, 1:2 and 2:1 were prepared by the solvent method(vacuum and reduced pressure rotary evaporation method), using melting point instrument and polarizing microscope. The physical and chemical properties of the coamorphous lurasidone hydrochloride-shikimic acid were investigated by methods such as HPLC and PXRD. RESULTS Among the three prepared coamorphous lurasidone-shikimic acid, the coamorphous one with a molar ratio of 1:2 was the most stable. CONCLUSION By increasing the ratio of shikimic acid, the stability of the coamorphous form can be improved.