Abstract: A novel brachytherapy instrument, β particle axillary odor therapeutic instrument (also known as β-particle axillary odor applicator), was successfully developed. The instrument mainly contains six parts including irradiator, supporter, lifter, shield cover, controller and treatment trolley. A full coverage therapy performed by the applicator can eliminate the axillary odor of patient. In this method, the ⁹⁰Sr/⁹⁰Y β radioactive source located in the irradiator is used to irradiate apocrine sweat gland under patient’s armpit. Preliminary clinical tests indicate that the therapeutic effect is definite whether immediate irradiation, or supplementary irradiation after operation for apocrine sweat gland. This instrument provides another painless, non-surgical and noninvasive treatment. It features a safe, effective, convenient and automatic operation.