Using corpus approach, a growing number of researchers blamed textbooks for neglecting important information on the use of grammatical structures in natural English. Likewise, the prescribed Malaysian English textbooks used in schools are reportedly prepared through a process of material development that involves intuition. Hence, a corpus-based study with the population that was sourced from five Malaysian English language textbooks (Forms 1-5) was adopted to identify modal auxiliary verbs’ order and ranking in both whole text-types and spoken text-type of these textbooks. The WordSmith Tools 4.0 was used almost entirely to support quantitative and qualitative data analysis in this research. This study has revealed that for almost all modal auxiliaries, there is a discrepancy between frequency order in the textbook corpus and natural English. The findings of this study also show that the currently used pedagogical language in Malaysian textbooks is mainly based on written rather than spoken English.