Ecological floating island is a combination of greening technology and floating technology, which generally consists of four parts, namely, floating island frame, plant floating bed, underwater fixing device and aquatic vegetation. The frame can be made of natural materials such as bamboo, wood strips, reed curtains, rattan, etc. The floating body for plant growth is generally made of light polymer materials, which is light and durable. The plants on the floating island generally choose all kinds of suitable terrestrial plants and wet plants. The underwater fixed design of artificial floating island is an important design content, which not only ensures that the floating island will not be taken away by the wind and waves, but also ensures that the collision between the floating island and the floating island can be buffered in the case of drastic changes in water level. When Japan studied the floating breakwater of the ocean, it once questioned the safety of the underwater fixed part, but the design of artificial floating island was aimed at lakes and marshes, and two lakes like Biwahu and Xiapu were the largest projects. Compared with the ocean, the designed external force is only 1/1 of that of the ocean, so the underwater fixation of artificial floating islands in Biwa Lake and Xiapu Lake is calculated with reference to the past marine buildings and coastal design, and the safe and reliable calculation results are obtained. The underwater fixation forms depend on the foundation conditions, and the commonly used ones are weight type, anchor type and Hangzhou type. In addition, in order to alleviate the collision between floating islands caused by water level changes, it is generally more common to set a small float between the floating island body and the underwater fixed end.