Background <p>Oats are widely consumed throughout the world because of their nutritive value, with their yield and quality being associated with the developmental process of grain development. However, the underlying molecular mechanisms of the transcriptional dynamics of this process have not yet been fully elucidated. In this study, RNA-seq was performed to investigate the transcriptional dynamics and identify the key genes involved in the development of the oat grain at four different developmental stages.</p> Results <p>A total of 33,197 differentially expressed genes (DEGs), including 1,308 differentially expressed transcription factors (TFs) were identified, 398 DEGs associated with plant hormone signal transduction and 107 DEGs associated with starch and sucrose metabolism. The main concern of this study was to include those genes associated with hormone signaling, and the sucrose and starch metabolism pathways.</p> Conclusions <p>The results of this study provide valuable insights into the genetic resources affecting the molecular mechanism underlying the development of the oat grain, as well as establishing a strong theoretical foundation for its improvement.</p>