Teachers' beliefs have been shown to have a significant impact on educational practice, particularly in the domain of grammar instruction, where teachers have strong opinions. Traditional grammar training is sometimes criticized for promoting lower order thinking and relying on rules of thumb rather than new language developments. A rising corpus of research on grammar instruction proposes that linguistics, conceptual knowledge, and introspective or higher-order thinking should be prioritized in grammar training. Generally, this present study explored the metalinguistic reflective beliefs and teachers' beliefs on grammar content knowledge. It hoped to address the gap on this problem of inquiry. This study employed a cross-sectional survey research design for 266 EFL Saudi teachers. A questionnaire was used as an instrument for data gathering in this study. Results showed that Saudi EFL teachers have a positive view of their metalinguistic reflective beliefs. They also have positive beliefs on grammar content knowledge. It also surfaced that there is a positive relationship between the two variables (metalinguistic reflectivity and grammar content knowledge), implying that when teachers have a high level of metalinguistic reflectivity beliefs, they highly manifest acceptable beliefs in teaching grammar content. Implications of this study will strengthen the language teaching skills of teachers to strengthen the grammar curriculum of the Saudi context.