BACKGROUND:Microcapsules is one of the main directions of targeted therapeutic dosing system. With a size of several microns to several hundred microns, it can be used for injection, oral, arterial administration and local treatment of targeted organs and other treatment approaches. OBJECTIVE: To prepare rhizoma drynariae total flavonoids/polylactic-co-glycolic acid microcapsules and optimize the preparation conditions. METHODS: The rhizoma drynariae total flavonoids/polylactic-co-glycolic acid microcapsules was prepared by ultrasonic emulsification. The effect of the mass concentration (60, 100, 140, 180 g/L), stirring speed (50, 1 000, 2 000, 4 000 r/minutes), colostrum emulsification time (2, 4, 6, 8 minutes), colostrum water oil ratio (1:5, 1:10, 1:15, 1:20) of rhizoma drynariae total flavonoids/polylactic-co-glycolic acid microcapsules on gross morphology, particle size distribution width and total flavonoids encapsulation efficiency of microcapsules was univariately analyzed. The rhizoma drynariae total flavonoids/polylactic-co-glycolic acid microcapsules with smaler particle size, uniform dispersion and higher encapsulation efficiency was filtered out. RESULTS AND CONCLUSION: The optimum process parameters were as folows: 140 g/L polylactic acid-glycolic acid solution, the stirring speed of 2 000 r/min, the colostrum emulsification time of 6 minutes, and the colostrum water-oil ratio of 1:15. The microcapsules prepared in the optimized process displayed a uniform distribution and its average particle size was (789.8±712.3) nm, which distributed relative narrowly and basicaly less than 5 μm. Microcapsules presented round, with a regular edge under scanning electron microscope. The average encapsulation efficiency was 47.72%.