The invention discloses a preservation method of fresh water fillets. The preservation method comprises the steps of slaughtering and filleting fresh water fish, modulating pickling liquid, and pickling, freezing and storing the fresh water fillets. By virtue of the preservation method, the fresh water fish is slaughtered and filleted, and the fillets are put into purified water and are subjected to vibration rinsing in a vibrator, so that the dirt of a fish body can be remarkably removed, and the quality guarantee and tenderness preservation of the fresh fish are benefited. Meanwhile, the fillets are pickled by virtue of the pickling liquid prepared from purified water, table salt, white granulated sugar and I+G, fish cells can reach an optimal salting-in state by virtue of normal saline, and fish muscle cells can be always protected in a stable state in subsequent freezing, storing and unfreezing stages, so that the loss of cell sap in the muscle cells can be reduced; by utilizing a proper amount of the white granulated sugar, the fish muscle cells always can be moist in the freezing, storing and unfreezing stages, and particularly, the water loss of the fish muscle cells after unfreezing is reduced; and by utilizing a certain amount of I+G, the decrease of the delicate flavor caused by freezing, storing and unfreezing can be remedied.