Systematic Studies on the

Based on the accurate macroscopic-microscopic mass formula and the experimental data of β-decay half-lives of the nuclei with atomic number ranging from 20 to 190, a systematic formula has been proposed to calculate β-decay half-lives of neutron-rich nuclei. The formula is proved to reproduce the experimental β-decay half-lives of neutron-rich nuclei very well, and then is used to study the r-process nucleosynthesis in models of high-entropy mass outflows. The calculated abundances show a good agreement with the solar r-abundances around the third peak and the rare earth mass region