GUI tests is crucial for ensuring software quality and user satisfaction of mobile apps. In practice, companies often maintain extensive test cases written in natural language. Testers need to convert these test cases into executable scripts for regression and compatibility testing. Requirement changes or version updates often necessitate the addition and modification to these test cases. Thus, when faced with large volumes of test cases and regular updates, this process becomes costly, which is a common challenge across the industry. To address this issue, this paper proposes ProphetAgent that can automatically synthesize executable GUI tests from the test cases written in natural language. % , and then execute the tests on the corresponding apps. ProphetAgent first constructs a Clustered UI Transition Graph (CUTG) enriched with semantic information, then leverages large language models to generate the executable test case based on CUTG and test cases written in natural language. Experiment results show that ProphetAgent achieved a 78.1% success rate across 120 test cases in Douyin, Doubao, and six open-source apps, surpassing existing automated approaches (21.4% for AppAgent and 32.5% for AutoDroid). Additionally, statistical data from ByteDance’s testing platform reveal that before implementing ProphetAgent, testers managed an average of 25 test cases per day, but this number has increased to 90 with ProphetAgent.