Abstract: Transitions and oscillator strength for highly ionized CoⅠ-like Rh¹⁸⁺ ions 3p⁶3d⁹-3p⁵3d¹⁰,3p⁶3d⁹-3p⁶3d⁸4p are calculated by using Cowan's multiconfiguration self-consistent field method together with the fitting formula proposed here.The calculations are in agreement with observations.