The present application relates to a coupling and a mechanical system. The coupling (10) includes: a first mounting base (11), including a first flange (11) and a first shaft (12) which are connected with each other, wherein the first flange (11) is configured to be connected to an engine (20); a second mounting base (2), including g a second shaft (22) and a second flange (21), wherein the second shaft (22) is sleeved outside the first shaft (12), and the second flange (21) is connected to an end, away from the first flange (11), of the second shaft (22) and is configured to be connected to a fan (40); a vibration damper (3), connected to the first flange (11) and sleeved outside the second shaft (22) for vibration damping; and at least one positioning member (4), the positioning member (4) having elasticity and being arranged between the first shaft (12) and the second mounting base (2) for supporting and positioning. Based on this, the performance of the coupling is effectively improved.