Abstract: The two-step method to get carnosic acid from rosemary leaves was employed.The first step was getting rosemary extracts from rosemary leaves by ultrasoundassisted ethanol extraction;the second step was to get purified carnosic acid from rosemary extracts by silica gel column chromatography.Results of single factor experiments showed that:the reasonable conditions of silica gel column chromatography were 200-300 mesh silica gel,the eluent ethyl acetate:petroleum ether(4:13,v/v),the flow rate 4mL/min and 0.5 g solid loaded.The purity of carnosic acid was ≥97% by this method.Meanwhile,through UV,IR,NMR,LC-MS to verify the substance obtained by experiment is carnosic acid.

Key words: carnosic acid, two-step method purification, identification