Based on the structure characteristics of China Southern Power Grid(CSG) after asynchronous interconnection, this paper proposes the black-start scheme of CSG based on Luxi Back-to-back VSC-HVDC System. Firstly, from the characteristics of asynchronous interconnection of Yunnan power grid and its impact on the target framework of the black-start stage of CSG, the advantages of Luxi Back-to-back VSC-HVDC being applied to power grid black-start are analyzed and the black-start strategy of VSC-HVDC system is proposed.Then, the VSC-HVDC based black-start scheme suitable for CSG is put forward, meanwhile the start-up paths and operation steps to restore Yunnan power grid and the main grid of CSG with Luxi Back-to-back VSC-HVDC system are presented. At last, field test and RTDS simulation verify the validity and effectiveness of the proposed black-start strategy.