Abstract: A doubled-haploid rice population,consisting of 81 DH lines derived from the F₁ hybrid of a cross between indica cultivar and japonica cultivar,was used to map quantitative trait loci(QTL) controlling numbers of vascular bundles in the peduncle and the top second internode,primary and secondary rachis branches,and spikelets per panicle.A total of 16 QTLs were detected.Among them,7 QTLs with larger effects each explained more than 20% of the total variation for the traits concerned.A cluster of 4 QTLs for the traits studied was located to the genomic region of about 35 cM in length flanked by the marker RZ776 and C11 on chromosome 1.This chromosome region from the parent ’Gui630’ contributed to the increasing phenotypic values of the 4 traits,viz.numbers of large vascular bundles in peduncle and top second internode,small vascular bundles in top second internode,and secondary rachis branches.The present paper also discussed the strategy for improving of vascular bundle system in peduncle via pyramiding favorable QTLs for the traits concerned using marker-assisted selection.