The invention discloses a double-way vibration separation device for a water chestnut combination harvester. The device comprises a rack, a front separation sieve plate hinged to the front portion inthe rack through an eccentric shaft, a rear separation sieve plate hinged to the rear portion in the rack through an eccentric shaft, a conveying belt, a toothed embedded clutch and a belt wheel conveying device, wherein the conveying belt and the toothed embedded clutch are arranged below the rear end of the rear separation sieve plate, the eccentric shafts at the same side are connected througha first chain wheel mechanism, and reset springs sleeve the two eccentric shafts of the first chain wheel mechanism respectively. Through a combing effect and a vibration effect of a threaded rod, high-viscosity soil on the surfaces of water chestnuts is removed, and the separation rate reaches 70-80%; stone, stems and leaves in a mixture are removed through an impact effect, and the separation rate reaches 90%; separation is complete, work is reliable, damage to the water chestnuts is small, the device can be arranged in the water chestnut combination harvester, the separation rate of the water chestnuts and the soil the removal rate of the soil are increased, the labor force is liberated, and the labor cost is lowered.