This paper is the first to simulate the evolution of American attitudes toward China over a 20-year period, from 2005 to the present, using a large-scale language model (LLM). To address a broad range of scenarios of evolving American perceptions of China, we propose a framework that integrates cognitive structures for media data collection, user profile generation, and opinion updates. Leveraging the LLM's capabilities, we extract objective news content, uncover the influence of biased media exposure and the sources of extreme opinion formation, and introduce a "devil's advocate" agent to explain the shift from negative to positive attitudes. The simulation results validate the framework and demonstrate the impact of biased framing and selection bias on attitude formation. In conclusion, this study presents a new paradigm for modeling cognitive behavior in large-scale, long-term, cross-national social contexts. This approach offers insights into the formation of international biases, provides insights into the factors that shape media consumers' perspectives, and contributes to reducing bias and promoting intercultural tolerance.