The multi-terminal VSC-HVDC transmission technology is developing rapidly and its reliability analysis is a prerequisite to ensure the safe and stable operation of the DC transmission system. Due to the lack of qualitative and quantitative assessment and study of improvement methods for the reliability of multi-terminal DC transmission systems at present，a kind of reliability modeling method for multi-terminal VSC-HVDC systems based on status spacial method and step-by-step combination model is proposed in this paper. The various practical operating status of multi-terminal VSC-HVDC transmission projects are considered in this method，the status transition models for DC line and subsystem of converter station are set up respectively. The correctness and feasibility of this method are verified by solving such reliability in-dicators as power supply availability and annual equivalent outage time. Finally，an analytical expression for the sensitivity of reliability index to component failure rates is set up by using the hierarchical equiva-lence method，and the weakest link of system reliability is quantitatively analyzed. The research can pro-vide some reference for the reliability assessment of actual VSC-HVDC projects.