High-porous algae-based modified flocculant is a fossil of diatoms, a single-celled marine microorganism from 200 million years ago, purified, activated, and modified through physical mineral processing methods to form an excellent water purification product. It is commonly used in beverage filtration, surface water quality purification, and wastewater treatment plant upgrading. The high-porous algae-based modified flocculant possesses multiple mechanisms such as flocculation, adsorption, biological carrier, and sludge reduction. It has a certain removal effect on organic pollutants, nutrients like nitrogen and phosphorus, and heavy metals in water bodies. It can also deodorize and decolorize. The dosage for general polluted water is about 0.0003%, and for severely polluted water, it does not exceed 0.0005%.