4 to 5 minutes. How long to cook razor clams should be strictly controlled, the cooking time is too short will not be cooked, can not completely kill the parasites in the razor clams, if the cooking time is too long will make the meat become old, the taste is bad. Therefore, it is best to steam the razor clams for 4 to 5 minutes in order to kill the parasites. Razor clams are an edible shellfish creature, raw razor clams have a large number of bacteria in the body, need to be cooked at high temperatures to sterilize.