Abstract: This study aims to evaluate the impact of the volatility of new energy generation on the carrying capacity of the power grid, and propose an evaluation method based on volatility analysis and simulation technology. This study collected and preprocessed data from a new energy generation project in Zhejiang Province, combined with Short-Time Fourier Transform(STFT) to analyze the fluctuation characteristics of wind farms and photovoltaic power stations, and constructed a dynamic simulation model of power grid carrying capacity to evaluate frequency stability, load allocation, and transmission system impact. The research results indicate that the volatility of wind and photovoltaic power generation has a significant impact on the frequency stability and load distribution of the power grid. The evaluation results show that the fluctuation amplitude of wind farm output power can reach ±37%, and the fluctuation amplitude of photovoltaic power plants can reach ±47%, leading to a maximum frequency deviation of ±0.42 Hz in the power grid, exceeding the safe range. In addition, the frequency of calling backup power sources has significantly increased, leading to a significant increase in equipment maintenance pressure. From this, it can be seen that the evaluation method proposed in this study provides a reliable reference for the operation evaluation of the power grid, which can effectively help to cope with the uncertainty challenges brought by new energy generation and improve the safety and stability of the power grid.