The Eimeria spp. parasitized in laboratory small animals(rats, mice, hamsters, guinea-pigs and rabbits) are numerous in number and high in frequency.And all the small laboratory animals should be free from all those Eimeria spp. Among Eimeria, only those parasitized in rabbits have been studied systematically, the others are still unknown to us. The following are our opinions based on the information we have. (1)Based on the host specificity of Eimeria, more than 30 spp. of Eimeria are divided into 5 animal groups in order to be easier in species identification. (2)The classification of Eimeria nowadays is based on the morphology of oocyst. It's difficult to distinguish when there are many kinds of Eimeria due to a variety of maturation degree. It's important to point out that both new and old samples are needed. The morphological regularity found by contrast is useful in species identification. (3)The morphology of oocyst is the main point of classification. The creditability of identification worud be increased by the combination judgement based on observing the whole process of Eimeria life-cycle, such as schizogony and gametogony reproduction in the intestinal cells, the needed time of the formation of occyst and the histological and pathological changes.