According to the chemistry characteristics of high-pressure oxygen and its supplying system requirements, some brass balls of DN4, DN10, DN20 and straight adapting pieces were designed by referring to Chinese space industry standard QJ2889 series about the adapting piece for 37° conical surface tube. Strength assessment, strength test and encapsulation test of specimens were made. The brass tube adapting pieces were applied in the high-pressure oxygen supplying system and the result satisfied the requirements of the high-pressure oxygen system. The difficulty of connection between brass tube and stainless steel tube was solved.