A BASIC program of Coulomb approximation for the calculation of atomic transition probability based on Trefftz s FORTRAN program is given. It is used to calculate the oscillator strength of Helium-like and Lithium-like isoelectronio sequences for the first ten elements. Oscillator strength and transition probability for heavier elements Cu Ⅰ and Cd Ⅱ, which are important in laser application, are tabulated. Branching ratio of some transitions for CdⅡ is calculated to obtain the charge transfer cross section for Cd-He II collision.