A shelf comprising a shelf plate and a bottle rack connected to the shelf plate pivotally and rotating between a folded position adjacent to the shelf plate and an unfolded position apart from the shelf plate, the shelf further comprises a rotary assembly connected with the shelf plate and the bottle rack and enabling the bottle rack to have at least two unfolded positions, the rotary assembly is enabling the bottle rack to rotatably be fixed at different unfolded positions, the rotary assembly comprises a first regulating part connected with the shelf plate, a second regulating part connected with the bottle rack and a concave-convex engagement structure comprising a first curved surface formed on the first regulating part and a second curved surface formed on the second regulating part; the first and second regulating parts (31,32) are connected rotatably relative to each other around a pivotal shaft, and the folded position and the at least two unfolded positions are provided in a circumferential direction of the pivotal shaft; when the first and second regulating parts (31, 32) are static relatively, the first curved surface abuts against the second curved surface; when the second regulating part rotates relative to the first regulating part, the second curved surface jumps to and fro in an axial direction of the pivotal shaft by getting apart from and adjacent to the first curved surface; the rotary assembly further comprises a reset part provided on one side of the first or second regulating part (31,32), and when the second regulating part rotates relative to the first regulating part, the reset part drives one of the first and second regulating parts (31,32) to restore to abut against the other of the first and second regulating parts (31,32), and the reset part and the pivotal shaft are provided on the same side of the first or second regulating parts (31,32); the bottle rack comprises a middle portion for laying a bottle and a connecting portion for connecting the middle portion to the shelf plate; the reset part is configured as the connecting portion which is bent and formed integrally relative to the middle portion; the pivotal shaft is formed as a free end of the connecting portion; characterized in that the connecting portion connects the middle portion to an open grove of the second regulating part and also to an accommodating groove of the first regulating part; the second regulating part is provided with the open groove for receiving the free end, the second regulating part further comprises a fixing part configured for sealing the open groove to prevent the free end from being separated from the open groove; the second regulating part is connected with the free end of the bottle rack through the open groove and the fixing part; the first regulating part is provided with the accommodating groove which receives the free end and is provided in a center of the first curved surface, such that the first and second regulating parts (31, 32) rotate around the free end. the rotary assembly comprises a first regulating part connected with the shelf plate, a second regulating part connected with the bottle rack and a concave-convex engagement structure comprising a first curved surface formed on the first regulating part and a second curved surface formed on the second regulating part; the first and second regulating parts (31,32) are connected rotatably relative to each other around a pivotal shaft, and the folded position and the at least two unfolded positions are provided in a circumferential direction of the pivotal shaft; when the first and second regulating parts (31, 32) are static relatively, the first curved surface abuts against the second curved surface; when the second regulating part rotates relative to the first regulating part, the second curved surface jumps to and fro in an axial direction of the pivotal shaft by getting apart from and adjacent to the first curved surface; the rotary assembly further comprises a reset part provided on one side of the first or second regulating part (31,32), and when the second regulating part rotates relative to the first regulating part, the reset part drives one of the first and second regulating parts (31,32) to restore to abut against the other of the first and second regulating parts (31,32), and the reset part and the pivotal shaft are provided on the same side of the first or second regulating parts (31,32); the bottle rack comprises a middle portion for laying a bottle and a connecting portion for connecting the middle portion to the shelf plate; the reset part is configured as the connecting portion which is bent and formed integrally relative to the middle portion; the pivotal shaft is formed as a free end of the connecting portion; characterized in that the connecting portion connects the middle portion to an open grove of the second regulating part and also to an accommodating groove of the first regulating part; the second regulating part is provided with the open groove for receiving the free end, the second regulating part further comprises a fixing part configured for sealing the open groove to prevent the free end from being separated from the open groove; the second regulating part is connected with the free end of the bottle rack through the open groove and the fixing part; the first regulating part is provided with the accommodating groove which receives the free end and is provided in a center of the first curved surface, such that the first and second regulating parts (31, 32) rotate around the free end.