The implementation of the dual carbon policy has resulted in a significant integration of renewable energy sources and new types of loads into the power grid, posing challenges to the safe and stable operation due to their intermittency and volatility. The problems of voltage stability have been emphasized as a result. The regional interconnection of power systems and improvements in grid infrastructure have enhanced transmission reliability, flexibility, and reduced fault probabilities. Consequently, there is an increasing focus on static voltage stability research which utilizes historical voltage data as a valuable record for assessment. This paper proposes a quantitative assessment for static voltage stability considering the accumulative effect of historical voltage curves. First, the calculation methods for assessing the fluctuation degree and voltage margin of historical voltage data are presented, and the historical voltage data impact factor is constructed. Then, the cumulative impact impedance modulus margin that takes into account the impact of historical voltage data is proposed. Finally, the IEEE 39-bus system was used to validate the proposed index. The results show that the proposed index has high reliability and can effectively assess power system static voltage stability.