Abstract: To prepare stearyl alcohol galactosidase modified gemcitabine hydrochloride nanoliposomes (18-GGNL) and optimize the prescription process using response surface methodology. METHODS The 18-GGNL was prepared by (NH4)2SO4 gradient method, the entrapment efficiency as the evaluation index, Box-Behnken response surface design method was used to optimize the formulation. The 18-GGNL was evaluated by encapsulation efficiency, drug loading, morphology, particle size, stability, and in vitro release. RESULTS The optimized formulation was as follows: the concentration of phospholipid was 3.10︰1, concentration of ammonium sulfate was 0.19 mol?L^-1, lipid ratio was 20.99︰1. The average of liposome entrapment efficiency was (70.8±0.95)%, the average particle size was(89.5±5.3)nm, the particle size distribution was narrow, good stability and slow release characteristics. CONCLUSION The (NH4)2SO4 gradient prepares 18-GGNL with good physical and chemical properties。