Abstract: The application of constructivist ideas in professional English writing teaching can help students construct meaningful understanding of course content while learning English, thereby improving their English writing and comprehension abilities. It enables students to explore course knowledge more deeply and ensures comprehensive improvement of students' professional English literacy under the influence of blended learning. Therefore, in the process of reforming and innovating professional English writing teaching activities, teachers should reexamine the guidance of constructivist ideas and choose constructivist theory, zone of proximal development theory, and input-output theory as guiding principles. They should explore group cooperative blended learning models, blended learning models in segmented classrooms, and blended learning models supported by communicative context creation. This approach effectively highlights the scientific and rational nature of educational reform and promotes high-quality advancement of professional English writing teaching.