The invention discloses a power coupling device. The power coupling device comprises an inner gear ring, a middle gear ring and an outer gear ring which are arranged coaxially and used for being connected with a power source. The inner gear ring comprises a first inner gear ring body and a second inner gear ring body. The outer circumferential portion of the first inner gear ring body is arrangedon the inner circumferential portion of the middle gear ring in a sleeved manner. The outer circumferential portion of the middle gear ring and the outer circumferential portion of the second inner gear ring body are arranged at the two ends of the inner circumferential portion of the outer gear ring in a sleeved manner correspondingly. The outer circumferential portion of the first inner gear ring body and the inner circumferential portion of the middle gear ring can be combined and separated through at least one first connecting part. The outer circumferential portion of the middle gear ringand the inner circumferential portion of the outer gear ring can be combined and separated through at least one second connecting part. The outer circumferential portion of the second inner gear ringbody and the inner circumferential portion of the outer gear ring can be combined and separated through at least one third connecting part. Due to the fact that the axial occupied space of the nestedgear ring structure is small, the structure is compact, and the integration level is high, the overall size of the power coupling device is small. The invention further discloses a hybrid power system including the above power coupling device and a vehicle including the hybrid power system.