Abstract: OBJECTIVE To prepare ibuprofen-resacetophenone conjugate (IB-RP) and evaluate its stability in vitro. METHODS Carbimide method was employed to prepare IB-RP, and its chemical structure was confirmed through infrared spectrum (IR), 1H-NMR and MS, respectively. The affect of different pH condition and rats plasma on the stability of IB-RP were observed and detected by HPLC. RESULTS The structure characterization results validated the synthesis of IB-RP. The stability of conjugate was affected by high temperature and the degradation rate was increased significantly under higher pH condition, too. In addition, IB-RP was degraded readily in rat plasma with 3 min half-life. CONCLUSION The preparation method of IB-RP is established, and its stability is influenced by pH value and plasma environment.