This work details a protocol for the isolation of Giardia species from their host animals and their identification based on their morphological and molecular characteristics. Giardia are intestinal protozoan parasites found in almost all vertebrates and the epidemiology of Giardia has attracted the attention of scientists due to their harm to humans and live stocks worldwide. Giardia trophozoites adhere to the surface of host's intestines using their ventral disc, and they also adhere the culture tube wall during in vitro culturing. We developed a method of isolating Giardia trophozoites according to this phenomenon, and a method of isolating Giardia cysts according to their special density as well. We validated the protocol by isolating and identifying Giardia species from their host animals, and all the results support that this methodology has a certain validity. It could help the further epidemiological researches and other researches requiring relatively pure living organism as materials of this harmful parasite.