The experimental beastie in this essay is only the rodent (rat, small rat, shrewmouse, cavy) and rabbit. The eimeria parasitizing in beastie are variety and frequency. Some of them are distinctly pathogeny and dangerous, so eimeria is one of debared parasites in “International Standards". All the eimerias in beastie are not touched in our country except rabbit eimeria reported systematically, so we aim to discuss it in this essay. The following are our opinions based on the information we have. 1. The 30 merias can be divided into 5 animal groups according to the eimeria’s special advocation characteristic. 2. The classification nowadays is based on the conformation characteristic. It is difficult to distinguish when there are many kinds of merias, because the maturate characteristics of oocyst are different. So it is better to see if the sample is new or old when you choose the material. You can find the rule by contrasting, so that the distinguish of species is easier. 3. The conformation of oocyst is the main point of classification. We can increase the creditability of defination by the colligate judgement of observing the transformation in organize pathology cooperating the entirely process of eimeria life history, such as the asexuality procreation and sexual reproduction of eimeria in intestines cell and the form of oocyst.