This study aims to analyze the impact mechanism and effect of reading-writing intervention on students' English writing proficiency through research on the English Reading-Writing Ability Improvement Program for International Novice Writers. Using quantitative research methods, it focuses on changes in participants' language expression ability, text reconstruction skills, and cross-cultural communication awareness after participating in the program. The research finds that interventions based on the input-output theory have significant effects: they not only help improve participants' vocabulary application ability and ability to handle complex sentence structures but also enhance the logical coherence of their discourses. Meanwhile, the intervention improves participants' ability to apply linguistic knowledge, metacognitive monitoring ability, and autonomous learning awareness. Through pre-test and post-test comparisons and writing sample analysis, this study confirms the role of systematic intervention in enhancing participants' comprehensive English writing ability. These findings provide empirical evidence for English writing teaching and theoretical support for promoting the innovation of international writing models.