DEAD BOX RNA HELICASES have been found to play a role in various aspects of RNA metabolism, ranging from synthesis, folding/unfolding, modification, processing, to RNA degradation. Rice DEAD BOX RNA HELICASE 51, OsRH51, is one of the RNA Helicase genes that has not been identified with its molecular function yet. Here we found that OsRH51 was highly expressed in reproductive organs such as stamen and carpel, and also in the immature seeds. The spatiotemporal analysis of β-Glucuronidase (GUS) staining also confirmed its expression in the reproductive organs, the developing seeds, shoots, and the root tips. Knockdown (Ri) and overexpression (OE) of OsRH51 caused a reduction in seed weight of up to 16% and 36%, respectively. In addition, more than fifty percent of the pollen was found to be delayed in the developmental process leading to up to 2-fold seed abortions. Moreover, Ri and OE produced shorter plant height and longer plant life cycles. Interestingly, seeds with twin embryos were discovered in the Ri and OE lines with clearly independent root and shoot axes attached to different scutellum, suggesting that they might have originated from different zygotic embryos. The phenotype displayed the similarity to auxin-related developmental defects. Furthermore, we found that Ri lines exhibited hypersensitivity to Auxin whereas OE lines were insensitive. Northern blot and circular reverse transcription-PCR (cRT-PCR) analyses indicated the unprocessed 18S pre-rRNAs were accumulated in Ri and OE lines. Our preliminary data suggest that OsRH51 is probably involved in the rice plant development and rRNA biogenesis.