Recovering system for slewing and braking energy of excavator

The invention provides a recovering system for slewing and braking energy of an excavator. A hydraulic energy accumulator serves as an energy storage element, a slewing motor/pump serves as an energy conversion element, inertia energy of a rotary table is converted into hydraulic energy and stored in the energy accumulator, namely, in the braking process, the slewing motor operates in the pump working condition, the slewing and braking energy of the excavator is recovered and stored in the energy accumulator, the energy is released during starting of the next time, by means of the control over energy distribution of an engine and the energy accumulator (a main power source and an auxiliary power source), the slewing and braking energy of the excavator is recovered and reused, and the purpose of energy saving is achieved.