Abstract: To maximize the use of the support power of wind farms and avoid the resource wastage, it is necessary to quantitatively assess the frequency regulation capability of the wind farm. However, the assessment of frequency regulation capability of the wind farm lacks a clear definition and is difficult to be assessed, and the mechanism of the impact of operational parameters and boundary constraints on support capability is unclear. To address this, indicators across multiple time scales, energy forms, and assessment levels are defined, which can accurately quantify the assessment of frequency regulation capability. Based on the proposed assessment indicators, by analyzing the mechanism of how operational parameters of wind farm affect frequency regulation capability, it is revealed that the rotational speed is the main influencing factor under low wind speed and low load shedding conditions, while load and capacity are the main influencing factors under high wind speed and high load shedding conditions. Furthermore, a method based on a nonlinear programming model is proposed for the precise calculation of assessment indicators. Finally, a case study analysis of a single-machine aggregated wind farm under droop and load shedding control in a four-machine two-area system validates the rationality of the proposed assessment indicators and the accuracy of the assessment method, as well as the correctness of the conclusions of the key influencing factor analysis.