Ethosomes, as a new vector for transdermal drug delivery, could obviously improve the transdermal penetration of drugs. In this study, we prepared testosterone undecanoate ethosomes, with TU ethosomes as the basic remedy, to determine its appearance, particle size, entrapment efficiency (EE) and membrane fluidity. Meanwhile, a transdermal test was conducted in mice, in order to determine the permeability characteristics of ethosomes as a vector for transdermal drug delivery, and compare transdermal behaviors of TU ethosomes, liposomes and their ethanol solutions.