Abstract: [Abstract]Objective: Adenosine deaminase 1 acting on dsRNA ( ADAR1) may be involved in the regulation of microRNA biogenesis and implicated in tumor development. Here we aimed to examine the of ADAR1 in oral squamous cell carcinoma (OSCC) and its influence on biological behavior of OSCC. Methods: The of ADAR1 in OSCC cell lines was tested by RT-qPCR and Western Blot. The of ADAR1 gene in OSCC cell lines was knocked down by siADAR1. Wound healing and Transwell test were used to detect migration and invasion of OSCC. RT-qPCR and Western Blot were used to detect epithelial-mesenchymal transition(EMT) markers Vimentin and E-cadherin, stemness markers Sox2 and Oct4, and OSCC-associated onco-microRNAs（miR-21-3p、miR-18a-3p、miR-210-3p、miR-155-5p、miR-181a-3p、miR-19a-3p）. Results: Higher ADAR1 was expressed in OSCC compared to normal oral mucosa. After ADAR1 knocked down, not only the migration and invasion of OSCC were significantly inhibited (P<0.05), but also EMT and stemness markers such as Vimentin, Sox2, and Oct4 decreased. Of note, OSCC-associated onco-microRNAs (miR-21-3p、miR-18a-3p、miR-210-3p、miR-155-5p、miR-181a-3p、miR-19a-3p) also decreased with ADAR1 gene knock down. Conclusions: ADAR1 is closely related with the biological behavior of OSCC. We speculate that ADAR1 may have impact on the biological behavior of OSCC by promoting mature microRNA processing.