Abstract: In a heat pipe furnace, Rb atoms, pumped by two-photon Doppler tree absorption (760.1 nm), are excited from the ground state 5S_1/2 to state 7S. Then the atoms are excited to the ionization state by Nd·YAG laser. The signals of the ions of Rb are amplified by the look-in amplifier and then enter the x-y record. Selected ionization signals of Rb⁸⁵ and Rb⁸⁷ are observed, and the isotope shift of Rb(7S) is obtained. The super-fine structure of Rb (5S→7S) has also been observed.