The invention provides a device for collecting and releasing marine plankton net samples. The device is characterized in that: a sample releasing switch of a sample collecting tube comprises an upper shell, a lower shell, a hopper and a sealing strip, wherein the sample collecting tube and the upper end of the lower shell are sealed and fixed together, and the center of the upper shell is provided with a through hole, of which the diameter is less than that of a spring; the outer wall on the lower part of the upper shell and the inner wall on the upper part of the lower shell are in sliding fit, a bottom plate provided with a sample releasing channel is fixed on the bottom part of the lower shell, the center of the bottom plate is provided with a hole, of which the diameter is less than that of the spring, and the bottom part of the lower shell and an opening of the hopper are sealed and fixed together; a connecting rod, of which the diameter of the middle segment is greater than those of both ends and both ends are provided with threads, is sleeved by the spring and penetrates the through hole, one end of the connecting rod is arranged in the hole on the center of the bottom plate, and the other end is fixed on the center of the sealing strip; and the connecting rod and the spring are proper in length, so that at the free state of the spring, the sealing strip can seal and separate the sample collecting tube and the upper shell. The device is good in sealing property, and one person can complete the collection and release of samples by using the device.