Theoretical Calculation of Atomic Structure: Relativistic Multichannel Theory Jun Yan 1, and Jia-Ming Li 1,2 1 Center of Atomic and Molecular Sciences, Department of Physics, Tsinghua University Beijing 100084, China 2 Institute of Physics, Chinese Academy of Sciences P.O. Box 603-22, Beijing 100080, China 1: Relativistic multichannel theory can calculate the physical parameter ($\mu_{\alpha}$,$U_{i\alpha}$) in MQDT for any atoms in both negative and positive energy ranges. 2: The calculated fine structure of nf Rydberg states for alkali atoms are in good agreement with measured values. 3: The atomic structures of high-Z atom Pb are also studied.