Redox reaction is a core chemical concept. However, its abstract nature makes it very difficult for students. Students' conceptual structure reflects their mastery of concepts, which helps teachers implement targeted educational strategies. This study aimed to explore the conceptual structures of redox reaction held by students (grades 10 to 12) by employing MDS and HCA. A total of 606 students participated, with 195 students in 10th grade, 202 in 11th grade, and 209 in 12th grade. The results indicated that three-dimensional solutions were appropriate for the conceptual structures of 10th and 12th graders, while 11th graders demonstrated two-dimensional solutions. All students grouped the 15 concepts related to redox reaction into two large clusters: metrology and the redox reaction process. Moreover, both 10th and 12th graders further subdivided the 15 concepts into four subclusters: metrology, oxidation process, reduction process, and chemical reaction. Students' conceptual structures were rational across all three grades. The conceptual structures of 10th and 12th graders were more refined than those of 11th graders, and there was no significant difference between the conceptual structures of 10th and 12th graders. 11th graders learned about electrochemistry and tended to confuse concepts related to redox reaction with those related to electrochemistry.