Sign language serves as the primary mode of communication for students with hearing impairment, particularly within special education settings. Teachers’ proficiency in sign language is therefore crucial to ensuring effective instruction, meaningful interaction, and positive learning outcomes. However, variations in sign language mastery among special education teachers may lead to communication barriers that negatively affect students’ comprehension, engagement, and motivation. This article aims to examine the level of sign language proficiency among special education teachers and its implications for communication with students with hearing impairment. Drawing upon existing literature and theoretical perspectives, this paper discusses key constructs related to teachers’ sign language knowledge and skills, classroom communication processes, and supporting factors that influence effective interaction. The review highlights that teachers with higher levels of sign language proficiency demonstrate clearer instructional delivery, stronger two-way interaction, and improved student participation. Furthermore, environmental, institutional, and emotional support factors are found to play a moderating role in strengthening communication effectiveness. The findings underscore the importance of systematic professional training, administrative support, and conducive learning environments to enhance teachers’ sign language competence. This article contributes to the growing body of literature on special education by emphasizing the central role of teacher communication competence in promoting inclusive and high-quality education for students with hearing impairment.