The invention discloses a rapid detection method for epitestosterone in a liquid cosmetic.The rapid detection method includes the following steps of preparing a spraying ionization device, wherein a borosilicate glass capillary tube (2) is drawn, and the spraying ionization device is assembled; detecting, wherein a solvent and a liquid cosmetic sample are sequentially injected into the borosilicate glass capillary tube (2), are fully mixed, extracted and layered to form an organic phase layer and a water phase layer, a metal microelectrode (1) is inserted into the organic phase layer from the back end of the borosilicate glass capillary tube (2), the parameters of an ion trap mass spectrometer are set, high voltage is applied to a metal clamp (4) through a high-voltage power source, electrospray is generated to be subjected to mass spectrometric analysis, positive ion mode detection is carried out, and a corresponding experimental map is obtained.The rapid detection method for the epitestosterone in the liquid cosmetic is low in cost and easy and convenient to operate, and rapid and accurate detection of the liquid cosmetic sample can be achieved.