Seaweed charcoal fiber is a fiber made by pulverizing the carbonized product of seaweed charcoal into ultrafine particles, and then mixing and spinning with polyester solution or nylon solution, and then spinning and processing. This fiber can be blended with natural cotton or other fibers, and the spun yarn has far-infrared radiation. Generally speaking, as long as 15% to 30% of seaweed carbon fiber is used, it has good far-infrared radiation performance, and can be woven into various fabrics with far-infrared radiation function, which can be used in products such as socks and underwear.