Dwarfism is one of the most important agronomic traits of rice.Fine mapping and functional studies of the plant height gene reveal the mechanisms for high yielding rice.In early research of this study,a main QTL Qph1 for plant height was mapped between the interval RM472-RM104 on the long arm of chromosome 1 in recombinant inbred line (RILs) population of Zhenshan 97B/Nanyangzhan.Then this QTL was used as a target fragment to construct a near isogenic line (NILs) BC3F2 whose genetic background was Zhenshan 97B.Firstly we detected the effect of Qph1 in NILs by a random population contained 320 plants,and it can explain 71.28% of phenotypic variation.Then the Qph1 was located between the interval RM6333-RM11961 through local QTL linkage analysis.In order to further reduce the target region,we planted a large genetic population which segregate in regions covering Qph1 and screened about 230 extreme recessive recombinant plants.The Qph1 locus was delimited to a 90 kb region flanked by SSR marker SHL4 and InDel marker HL13 by overlapping mapping，and compared with the sd1 has been cloned and found that they were not in the same area.It is a good foundation for cloning of the QTL.