This action research study investigated the effectiveness of an academic English writing course reform for postgraduate students in science and technology disciplines at a Chinese university. The reform integrated interdisciplinary teaching approaches, genre-based pedagogy, collaborative learning, and AI-assisted writing tools to enhance students' academic writing skills, engagement, and satisfaction. A mixed-methods approach was employed, including pre- and post-tests, student surveys, interviews, and writing samples. The results showed significant improvements in students' overall writing performance, particularly in the dimensions of organization and language use. Comparative analyses across disciplines revealed the universality of the interdisciplinary teaching approach in promoting students' mastery of academic writing conventions and professional terminology. The integration of AI-assisted writing tools, while offering potential benefits, also highlighted challenges that require careful consideration and management. The study provides valuable pedagogical implications, emphasizing the adoption of an interdisciplinary, genre-based teaching approach, systematic teacher training in innovative pedagogies, judicious incorporation of AI-assisted writing tools, and ongoing, multidimensional writing assessment and feedback. Future research directions are proposed, including longitudinal studies, comparative analyses of AI-assisted writing tools, ethnographic explorations of writer and instructor identities, design-based research on innovative writing curricula, and cross-cultural investigations of the transferability of teaching reform measures. This study contributes to the advancement of academic writing instruction in postgraduate education and offers insights into the effective integration of technology and pedagogy in English for Academic Purposes.