The development of the semiconductor industry promotes the transformation of integrated circuit design and manufacturing from a single IC, ASIC to SoC, and SoC from a digital SoC to a mixed-signal SoC, becoming a system-level chip in the true sense. Mixed-signal SoC design faces many new challenges, and the complexity of design calls for new design methods and tools. The traditional "Bottom-Up" and "Top-Down" design methods that have been applied to engineering practice cannot meet the requirements of integrated circuit design development. Through behavior-level design as a bridge between system-level and line-level design, a variety of design paths are realized, and the meaning of mixed-signal simulation is expanded. Mixed-signal hardware description language has the ability to describe digital circuits and analog circuits, and has the ability to describe system behavior and circuit performance. It has become a better choice for system-level and behavior-level design. Analog circuit is the bottleneck of mixed-signal integrated circuit design, so the research focus of this thesis is the behavior-level modeling of analog circuit. The dissertation focuses on the mixed-signal system, the DC-DC converter, and analyzes the working principle, control mode and working mode of the DC-DC converter. Based on the analysis of the external performance and internal structure of the various modules of the voltage-mode BUCK DC-DC converter, a mathematical model is established, and the mixed-signal hardware description language-Verilog-AMS is used to establish its behavior-level model, and verify the correctness and accuracy of the model. reliability. Use the behavioral model to analyze the stability and design the compensation network. Based on the discussion of the mixed-signal simulation verification process and tools, the simulation results of the behavioral model and the transistor-level model of the voltage mode BUCK DC-DC converter XD6529 are compared and analyzed, and the mixed simulation of digital and analog, and different abstract level descriptions is realized, and the simulation results are improved. Efficiency, to achieve a reasonable allocation of resources.