This paper presents a statistical analysis of English vocabulary across different educational stages in China, including primary school, junior middle school, senior high school, and university levels. The study examines the relationship between word length and educational stage, as well as the distribution patterns of word-initial letters across stages. A stage-specific vocabulary dataset was constructed, incorporating word lists, frequency data, textbook positioning, word length statistics, and initial-letter distributions. Based on this dataset, correlations were established between word length and educational stage, and between lexical difficulty and progression in schooling. The findings offer data-driven theoretical support for the design of English language teaching and examinations tailored to different educational levels.