A cap assembly for a power battery, the cap assembly comprises: a cap plate including a top surface, a bottom surface opposed to the top surface in a thickness direction, and a liquid injection hole penetrating through the cap plate from the top surface to the bottom surface and having an inlet provided on the top surface and an outlet provided on the bottom surface; and a blocking member provided on the bottom surface of the cap plate, wherein a projection of the blocking member in the thickness direction completely covers the outlet of the liquid injection hole, wherein a fluid channel is formed between the blocking member and the cap plate, and the fluid channel communicates with the outlet of the liquid injection hole, wherein the fluid channel is formed at a predetermined angle relative to an axis of the liquid injection hole and has a liquid outlet, so that an electrolyte discharging from the outlet of the liquid injection hole discharges from the liquid outlet of the fluid channel formed by the blocking member and the cap plate after turning at the predetermined angle, wherein the cap plate comprises a first end and a second end opposed to the first end in a length direction, and the liquid outlet of the fluid channel faces the first end or faces away from the first end in the length direction, characterized in that, the blocking member and the cap plate are formed as an integral structure, the liquid injection hole and the blocking member are provided at the first end, the cap assembly further comprises a vent plate which is disposed on the top surface and covers the liquid injection hole, wherein an annular seam is formed between an edge of the vent plate and the top surface of the cap plate, so that the vent plate and the cap plate are hermetically connected, and the axis of the liquid injection hole is offset from an axis of the vent plate, and the axis of the vent plate is closer to the first end or the second end of the cap plate than the axis of the liquid injection hole. a cap plate including a top surface, a bottom surface opposed to the top surface in a thickness direction, and a liquid injection hole penetrating through the cap plate from the top surface to the bottom surface and having an inlet provided on the top surface and an outlet provided on the bottom surface; and a blocking member provided on the bottom surface of the cap plate, wherein a projection of the blocking member in the thickness direction completely covers the outlet of the liquid injection hole, wherein a fluid channel is formed between the blocking member and the cap plate, and the fluid channel communicates with the outlet of the liquid injection hole, wherein the fluid channel is formed at a predetermined angle relative to an axis of the liquid injection hole and has a liquid outlet, so that an electrolyte discharging from the outlet of the liquid injection hole discharges from the liquid outlet of the fluid channel formed by the blocking member and the cap plate after turning at the predetermined angle, wherein the cap plate comprises a first end and a second end opposed to the first end in a length direction, and the liquid outlet of the fluid channel faces the first end or faces away from the first end in the length direction, characterized in that, the blocking member and the cap plate are formed as an integral structure, the liquid injection hole and the blocking member are provided at the first end, the cap assembly further comprises a vent plate which is disposed on the top surface and covers the liquid injection hole, wherein an annular seam is formed between an edge of the vent plate and the top surface of the cap plate, so that the vent plate and the cap plate are hermetically connected, and the axis of the liquid injection hole is offset from an axis of the vent plate, and the axis of the vent plate is closer to the first end or the second end of the cap plate than the axis of the liquid injection hole.