Disclosed herein are novel designs of a nasal cannula device suitable for supplying a flow of respiratory gas to a user during respiratory therapy. In one design, the nasal cannula device includes a cannula body, and a base. The cannula body has a front, top, and rear sides, in which the rear side is substantially longer than the front side and flattens out at both ends in the form of a wing, and a tab extending out from the lower end of the rear side. At least one nasal joint tube extends out from the top side of the cannula body, and a first connecting member is formed on the tab. The base includes, an opening formed on the top of the base; two through holes respectively formed on the left and right ends of the base; and a second connecting member formed on the bottom of the base. The first and second connecting members are configured to engage with each other thereby enclosing the base within a space collectively defined by the front, top, and rear sides, and the tab of the cannula body. In another design, the nasal cannula device includes a cannula body having a tubular body, in which one side of the tubular body is substantially longer than the rest of the tubular body and flattens out at both ends in the form of a wing, and a nasal joint tube extends out from the outer surface of the cannula body.