The invention discloses a multielement hybrid power system for an excavator. An oil outlet P of a hydraulic pump is connected with a port P of a first reversing valve and a port P of an eighth reversing valve, a port A of the first reversing valve and a port A of the eighth reversing valve are connected with a port A of the hydraulic pump/motor and a first energy accumulator, the hydraulic pump/motor is connected with a flywheel through a clutch, a port B of the hydraulic pump/motor is connected with a port A of a seventh reversing valve, a port P of the seventh reversing valve is connected with a port P of a third reversing valve, a port P of a second reversing valve and a port P of a fifth reversing valve, a port A of the second reversing valve and a port A of the third reversing valve are connected with a rodless cavity and a rod cavity of a swing arm hydraulic cylinder correspondingly, a port A of the fifth reversing valve is connected with a second energy accumulator, a sixth reversing valve is in parallel connection with the hydraulic pump/motor, and a port P and a port T of a fourth reversing valve are connected with a port A of the second reversing valve and an oil tank. Through the system, effective recycling of swing arm potential energy can be achieved, and during requiring, stored energy can be comprehensively reused.