Horseshoe crab is a kind of marine life，which began four hundred million years ago and is called “living fossils”. In history，there were many records about horseshoe crabs in China，with “sailing on horseshoe crabs and turtles” being the earliest，written in “To the Capital of Wu” by Zuo Si in the Western Jin Dynasty. From the Jin Dynasty to the Tang Dynasty，the understanding of horseshoe crabs was mainly focused on the shapes，living habits and the primary utilization of horseshoe crabs. From the Song Dynasty to the middle of the Qing Dynasty，the pharmacological description was added，besides the traditional contents and the description of the shape，living habits and utilization became more detailed. There are pictures of horseshoe crabs since the Ming Dynasty. The drawings of the court and the drawings by ordinary people exited aside，with the former realistic and the latter untrue. Up to the Republic，the drawings became scientific and standard. In the late Qing dynasty，the record of horseshoe crab began to follow the foreign natural history. From the 1930s，the understanding of horseshoe crabs mainly based on the discovery of western science. On the base of the progress of understanding，the utilization became varied，making horseshoe crabs into sauce，medicine，cups，hats，juries，scratching sticks，spoons，joss sticks，sacrifice，fertilizer，mainly used as food and medicine. Before Opium War I，the geographical distribution of horseshoe crabs south of Five Ridges was along the coast. From the Opium War to the founding of the People’s Republic of China，the horseshoe crabs along the coast south of Five Ridges decreased but in small scale. From the founding of the People’s Republic of China up to now，no horseshoe crabs can be found north of the mouth of the Pearl River. The sources of horseshoe crabs declined rapidly during the last 40 years. The decline was mainly caused by humans. Lack of the concept of protection and the increase of need of food and even greater need of industry，people caught and killed too many horseshoe crabs. From the 1970s to the 1980s，the fishery technique progressed rapidly and it became easier to catch horseshoe crabs. Filling the sea to grow the grain，getting the sea sand，growing seafood along the coast，and pollution spoiled the habitat of horseshoe crabs，causing the decline. The research on the history of utilization of horseshoe crabs，especially the history of their distribution，can help with the protection of horseshoe crab sources.