Second language (L2) writing plays an important role in improving the learners' language skills of English as a Foreign Language (EFL) in terms of language expression and linguistic thinking. Therefore, improving writing skills is still a focus area for EFL learners. To enhance EFL learners' writing ability and optimize their writing quality, an intelligent-based cognitive diagnostic feedback (I-CDF) strategy is proposed based on the Intelligent Writing Critique System (IWCS). IWCS can provide feedback on students' English writing learning components, including lexical, syntactic, rhetorical expression, chapter structure, and discourse intention. Hence, the study intends to assess the effects of feedback strategies based on students' writing scores, self-efficacy, epistemic network structure, and transferability. A quasi-experiment was conducted in two classes at a university in southeastern China, where students were randomly divided into two classes. One (N = 32) was considered an experimental group conducted using the proposed I-CDF strategy, while the other (N = 30) was the control group using the score-based teacher corrective feedback (S-TCF) strategy. The writing experiment lasted for seven weeks. The students would be interviewed at the end of the writing learning activities. The results indicated that the I-CDF strategy improved students' writing scores and self-efficacy. Furthermore, the epistemic network analysis showed that, compared to the control group, the I-CDF strategy encouraged the students to devote more energy to focus on high-level applications of writing skills such as rhetorical expression and sentence structure collation, optimizing the students' writing epistemic network of the writing of the students. The interview revealed that the I-CDF strategy supported the experimental group students' accurate understanding of writing, strengthening the logical structure of the writing. At the same time, the students in the experimental group were satisfied with the I-CDF strategy.