Abstract: Frequency-agile (frequency-hopping) radar technology is a key approach to enhancing anti-jamming capability, and the quantitative analysis and efficient simulation of frequency hopping against jamming represent core requirements in modern radar electronic countermeasure (ECM) simulation systems. To address the high computational complexity of conventional signal-level simulations and their limitations in supporting rapid system-level analysis, this work focuses on the confrontation between frequency-hopping radars and jammers. Specifically, quantitative models are developed for frequency interception probability, effective jamming-to-signal ratio, radar countermeasure success rate, and effective detection range. Furthermore, a functional-level simulation framework is established to reproduce the entire process of “radar frequency hopping–jamming reconnaissance/suppression–radar countermeasure.” The proposed quantitative models and functional-level simulation method provide both theoretical support and efficient analytical tools for implementing frequency-agile radars within ECM system-level simulations.