The Classic of Mountains and Seas was an ancient geographical document that recorded the geography, geography, animals, plants, myths and legends of China and its surrounding areas. The mythical beasts in the Classic of Mountains and Seas referred to some mythical creatures that existed under the geographical, geological, climate, and environmental conditions of that time. Due to various reasons, these mythical beasts no longer existed under the geographical, geological, climate, and environmental conditions of modern times. The disappearance of the mythical beasts may be due to their huge size and extraordinary abilities, which posed a great threat to the society and natural environment at that time. For example, some divine beasts had powerful offensive and defensive powers that might affect human activities and survival. In addition, the appearance and disappearance of divine beasts may also be related to political, religious, cultural and other factors at that time. It should be noted that the mythical beasts in the Classic of Mountains and Seas were not modern fictional creatures, but real creatures that existed in ancient times. They had certain historical and cultural value.