In wild animals, trematodes can result adversely impact the health and survival. Cyclocoelidae Stossich, large digenean bird parasites, lacks of molecular analysis that reclassi cations have not been supported.This study produced the rst fully determined and annotated mitochondrial genome sequence for the trematode Morishitium polonicum. The whole length of the M. polonicum (GenBank accession number: OP930879) mitogenome is 14083 bp, containing 22 transfer ribonucleic acids (tRNAs), 2 ribosomal RNAs (rRNAs, rrnL and rrnS), and a non-coding control section (D-loop) 13777 to 13854 bp in length. The 12 PCGs area has 3269 codons and a total length of 10053 bp, which making up 71.38% of the mitochondrial genome ' s overall sequence. Most (10/12) of the PCGs that code for proteins began with ATG, while the nad4L and nad1 genes had a GTG start codon. Phylogenetic analysis using the concatenated nucleotide sequences of 12 PCGs, and the ML tree analysis results showed that M. polonicum is more closely related to with Echinostomatidae and Fasciolidae, which indicates that the family Cyclocoelidae is more closely associated with these Echinochasmidae. This study will provide mtDNA information, increasing analysis of mitogenomic structure and evolution. Moreover, understand the phylogenetic relationship of the uke.