Abstract: A dynamic reactive power demand assessment method considering large-scale wind power access is proposed in this paper.Firstly, the random matrix theory is applied to identify weak voltage nodes and areas in power system where the large-scale wind farm cluster is integrated. If the area where the wind farm cluster is integrated is the weak voltage area, the wind farm cluster enters the predecision link of emergency voltage control. Secondly, the calculation model of transient voltage stability index in weak areas is established based on BP neural network, and a sensitivity based dynamic reactive power demand assessment method was proposed.Finally, the effectiveness of the proposed method is verified on the IEEE 10 machine 39 bus system connected to the wind farm group.