The large-scale integration of renewable energy into the grid poses challenges to the frequency regulation of the power system. Reasonably determining the regulation capacity demand is of great significance for maintaining frequency stability and improving the operational efficiency of the power system. This paper proposes a frequency regulation capacity demand estimation method considering regional area control area (ACE). Firstly, the spatiotemporal characteristics of the output of renewable energy stations are calculated based on kernel density estimation (KDE), confirming the smoothing effect of renewable power stations and the time-segment characteristics of forecast error distribution. Then, the correlation between regulation capacity demand and various variables is calculated, employing a multiple linear regression (MLR) model to estimate the regulation capacity demand of the power system. Finally, the proposed method’s effectiveness is confirmed using actual operating data from a regional power system. The results indicate that the regulation capacity demand determined by the method proposed in this paper is more reasonable compared to the traditional approach.