Filming-rehydration and ultrasonic method were combined to prepare ethosomes as a carrier of triptolide. A laser dynamic scattering instrument was used to determine the particle size of ethosomes. The average particle size was calculated based on the measurements of five different batches of ethosomes. To determine the entrapment efficiency, free triptolide was isolated by ultracentrifugation. The concentration of triptolide was then determined using high-performance liquid chromatography (HPLC). There was an inverse relation between the average size of the triptolide ethosomes and the concentration of ethanol, and the size increased as the phospholipid concentration increased; the entrapment efficiency of ethosomes increased with the increasing concentrations of ethanol and phospholipid. An optimal formulation was obtained when lecithin and ethanol were 2% (w/v) and 45% (v/v), respectively. Triptolide ethosomes exhibited a small particle size, even distribution and high entrapment efficiency (98%). Ethosomes have high entrapment efficiency, a good percutaneous permeability and qualities that make them particularly suitable to serve as a liposome drug carrier. The concentration of ethanol and phospholipids developed a positive impact on entrapment efficiency. Triptolide ethosomes with a ratio of 2% (w/v) lecithin to 45% ethanol (v/v) have, relatively, a small particle size, even distribution and high entrapment efficiency. Key words: Ethosomes, triptolide, liposome.