High-voltage direct current transmission based on voltage-source converter（VSC-HVDC） transmission doesn’t rely on receiving end to provide commutating current. VSC-HVDC links can access in weak alternative current（AC） systems. However

operation characteristics that VSC-HVDC links access to weak AC systems need to be studied. Consequently

we established mathematical models of actual weak power systems and VSC-HVDC links. From view of max transmission power

we analyzed influence factors that restrict VSC-HVDC links to access in weak AC systems. Combined with power flow equations in AC side and stable operation condition

theoretical critical SCR that VSC-HVDC transmission accesses to weak AC power network was obtained. Moreover

theoretical analysis was verified in BPA software.The simulation results demonstrate that the proposed measures should be taken if receiving ernd’s SCR is less than 1.4 to ensure systerms stablility. The results can provide the theoretical guidance for VSC-HVDC industrial application access to weak AC power grid in actual projects.