The utility model discloses a coaxial adaptor, which comprises an outer conductor and an inner conductor arranged inside the outer conductor, wherein one end of the inner conductor extends out of the outer conductor and is connected with a detected hard connector, and the other end of the inner conductor forms an inner core of a standard connector joint arranged on the outer conductor. The coaxial adapter is detachably connected between two tested connectors directly without a special PCB (printed circuit board) circuit adapting board, and is convenient in mounting and demounting, small in occupied space, difficult to wear and long in service life.