About 8-15 minutes. Oysters are shell molluscs that are relatively easy to cook. If the meat is boiled directly in water, the meat will be fully exposed to water, so it will usually be fully cooked in about 8-10 minutes after the water is boiled. This kind of Do not cook it for too long to avoid overcooking it and causing the meat to become old; if it is a full-shell oyster, you need to cook it for about 15 minutes, or if the oyster shell is opened, it means that the oyster is cooked. Boiling the whole shell is good It retains the taste and texture of the oysters, and it is easier to tell whether the oysters are cooked or not.