As the most common cause of the human microsporidiosis, Enterocytozoon bieneusi has been found in a wide variety of animal hosts. Deers are the ruminant mammals living in a variety of biomes, and the distribution of deer species differ by geography. To understand the prevalence of natural infection of E. bieneusi in deer and to assess their epidemiological role in the transmission of microsporidiosis caused by E. bieneusi, 91 fecal specimens were collected from 86 sika deers and five red deers in the northeast of China. By PCR and sequencing of the internal transcribed spacer (ITS) region of the ribosomal RNA (rRNA) gene of E. bieneusi, an average infection rate of 31.9% (29/91) was observed in deer, with 32.6% (28/86) for sika deer, and 20% (1/5) for red deer. Six ITS genotypes were identified: one known genotype BEB6 (n = 20) and five novel genotypes HLJD-I to HLJD-IV (one each) and HLJD-V (n = 5). A phylogenetic analysis based on a neighbor-joining tree of the ITS gene sequences of E. bieneusi indicated that genotypes HLJD-II and HLJD-III fell into group 1 of zoonotic potential, while the other genotypes (BEB6, HLJD-I, HLJD-IV, HLJD-V) were clustered into so-called bovine-specific group 2. This is the first report of E. bieneusi in deer in China. The observation of genotype BEB6 in humans previously and in deer here and also the findings of the two novel genotypes (HLJD-II to HLJ-III) belonging to potential zoonotic group 1 suggested the possibility of deer in the transmission of E. bieneusi to humans.