The invention relates to a ring structure for fixing a mobile terminal on a finger. The ring structure comprises a substrate, a slide assembly, an inverted-T-shaped rotary column, an intermediate connection piece and a ring fastener. The slide assembly is installed on the substrate. The inverted-T-shaped rotary column is installed on the slide assembly and can rotate. The intermediate connection piece is hinged with the upper end of the inverted-T-shaped rotary column by virtue of a first hinge pin shaft, the upper end of the intermediate connection piece is hinged with the ring fastener by virtue of a second hinge pin shaft, and the first hinge pin shaft and the second hinge pin shaft are parallel to each other. An intermediate clamping groove is formed in the ring fastener, after the ring fastener is overturned downwards along the second hinge pin shaft, and the intermediate connection piece can be clamped in the intermediate clamping groove. When not in use, the ring fastener and the intermediate connection piece can be stored in a folding manner. The ring structure does not comprise a mobile protection shell, is not limited by the mobile protection shell, can be applied to any handheld mobile terminal (such as a mobile phone) and is high in universality and convenient to use. In the circumstance that the protection shell is not needed, the mobile terminal can be fixed on the finger, the finger can be freed, the fatigue of the fingers caused by long-term holding can be alleviated, and the mobile phone also can be prevented from sliding or dropping.