Abstract: A encapsulated cotton panicle mutant (ecp1) was obtained by screening the tissue culture and variant progenies of restorer line Minghui 86 of indica rice. The encapsulated cotton panicle mutant showed abnormal rice heading during the growth period, and its spikelet was enveloped by white cotton-like material, which could not form normal rice spike, and thus could not seed. The genetic analysis showed that ecp1 was controlled by a single recessive nuclear gene. F₂ colony from a hybrid of indica rice variety 93-11 and ecp1 mutant was used to locate ecp1 in the region of about 240 kb on chromosome 8 of rice by SSR and InDel markers. The results of this study laid a foundation for the cloning and functional analysis of ecp1 gene.