The spikelet is a unique structure of grass plants, and its development involved with complicated molecular regulation network. nsg (nonstop glumes) mutant affecting spikelet development was identified from EMS-treated Jinhui10 (Oryza sativa L. ssp. indica.). Mutant plants had normal glumes (inner rudimentary glume, empty glumes and lemma/palea) and pedicel at the early flowering stage, but had longer ones at later stage. An extra glume-like organ was found in 84 % of mutant individuals. The number of stamens decreased in most mutant individuals whereas three stigmas or two carpels were found in some mutant individuals. The mutant phenotype suggests that NSG is involved in the whole rice spikelet development. NSG was mapped to a 15 kb region on the chromosome 4. According to sequence analysis, a gene encoding a protein with C2H2 domain exhibited a 13 bp insertion, causing a frame shift in genomics DNA and cDNA in nsg. This gene was identified as the candidated gene of NSG. The mutation of NSG influenced the transcription level of some floral hometic genes. The expression of OsMADS4, OsMADS16, DL and OsMADS3 decreased distinctly, and OsMADS1 increased in nsg panicle, suggests that NSG affected spikelet development through influencing the expression of floral hometic genes.