Abstract: OBJECTIVE To prepare brain targeting brain derived neurotrophic factor-flexible nano liposome(BDNF-FNL), screening and optimization of preparation process using the brain derived neurotrophic factor (BDNF) as model drug, and to evaluate the quality of preparation. METHODS Intranasal brain targeting drug delivery system of BDNF-FNL were prepared by injection. The evaluation index were the morphology, particle size, entrapment efficiency and Zeta potential. The size distribution of BDNF-FNL were studied that related to influences of stirring temperature, stirring speed and the volume ratio of alcohol to water. And orthogonal design was adopted to obtain the optimal preparation technology based on the influences. Drug brain targeting delivery efficiency of flexible nano liposome was evlauted by determination of BDNF concentration in the brain. RESULTS The results of orthogonal test showed that the best preparation method was as follows: stirring temperature was 30 ℃, stirring speed was 600 r·min^-1 and the volume ratio of alcohol to water was 1∶5. BDNF-FNL were round shape, particle size of (178.7±22.1) nm, and zeta potential of -29.8 mV. The preparation of stable storage for 30 d at 4 ℃, relative humidity (60±10)% conditions. Compared with the BDNF solution group, the group of BDNF-FNL could increase the concentration of BDNF in the brain for nearly 3 times, and the difference between two groups was statistically significant(P<0.05 or P<0.01). CONCLUSION BDNF-FNL prepared in the best process can significantly improve the drug concentration of BDNF in the brain.