The invention discloses a sampling device and a sampling method for a pond-culture flatfish, and belongs to the field of marine fish culture equipment. The sampling method comprises a funnel-shaped outer net cage, a large funnel net, a small funnel net, a large bamboo circle, a small bamboo circle, a stay bar, an edge line, a float line, a sinker line, a buoy, a buoy rope, a cross rope anchorage, a tail end anchorage, a tail end rope, a tail end anchorage line and a cross rope, wherein the sampling device is paved in a pond during sampling, and is taken in the next day, so that the requirements that regular sampling observation analysis is needed in the bastard halibut culture process and the sample n is greater than or equal to 30 are met; and the fish body is free of injury. The sampling device is low in price, simple in structure, easy to manufacture, and convenient to operate; the number of collected samples is ensured; the injuries to the fish body are reduced or avoided; the sample deviation is relatively small; and the condition of the pond-culture flatfish population can be really reflected.