Abstract: 【Objective】Mapping and cloning of rice flower organ genes could provide novel materials for advanced molecular mechanism research of rice spikelet development.【Method】 The flower organs and grain morphological characters of indica rice variety Shayouxuan 2(lsl098)with long sterile lemma phenotype and line 9311 with normal phenotype were observed at the booting and maturity stages. Rice 9311 was crossed with lsl098 to develop F₂ population which was applied to genetic analysis,gene mapping and sequencing analysis of long sterile lemma(Oslslgene.【Result】 Morphological observation srevealed that the long sterile lemma phenotype of lsl098 could be observed at the fifth stage of young panicle differentiation. At maturity,the long sterile lemma was similar to the lemma. It showed a"V"form which did not affect seed setting rate and germination rate. Genetic analysis showed that, the numbers of long sterile lemma plants obtained by forward and reverse crossing were 155 and 208 respectively,and they conformed to a separation of 1:3(x²_1:3 < x² _{0.05, 1}=3.84) comapred with normal phenotypic plants in F₂ populations,indicating that the phenotype was controlled by one pair of recessive genes. Two DNA bulks containing long sterile lemma plants and normal plants respectively were developed which were applied to identify co-segregated molecular markers associated with long sterile lemma phenotypes using a bulked segregant analysis method. Furthermore, the genotype and phenotype of recombinant plants were screened. As a result,Oslsl was located between markers 7M063 and G01031 on the short arm of chromosome 7. The physical distance of two markers was 838.8 kb according to the genome of Nipponbare. One cloned long sterile lemma gene G1 (LOC_Os07g04670)was harbored in the target region. Genomic sequencing analysis showed that lsl098 included 3 SNP mutations,2 bp insertion and 145 bp deletion comparing with that of 9311 or Nipponbare.【Conclusion】Gene Oslsl derived from lsl098 is a new allele of G1 gene which has been cloned al ready.