Eimeria parasites as importantly obligate intracellular apicomplexan protists can cause coccidiosis,resulting in high economical loss in the poultry industry annually.Genes function analysis of potential antigen candidates of these species is a vital step for the development of an efficient vaccine.CRISPR/Cas9(clustered regularly interspaced short palindromic repeats and Cas9 endonuclease),as a rapidly and efficiently gene editing tool has been developed and successfully applied to modify the genomes of many organisms,including apicomplexan parasites,Plasmodiumfalciparum and Toxoplasma gondii.In the present study,with CRISPR/Cas9 system containing the guide RNA and Cas9 nuclease,we can efficiently disrupt the targeted yfp gene in transgenic Eimeria tenella EtM2e line and a robust decrease in fluorescence rate(100%down to 56%)is consequence of the yfp gene mutation.We demonstrate the high-efficiency genome editing tool will allow us to introduce point mutations and epitope tags into E.tenella genome.Together,these methods will dramatically improve our ability to manipulate Eimeria spp.genome in the future study.