A constitutive gene (TIGR Locus:Loc_ Os07g34589) was obtained by combining our lab’s database with RT-PCR verification.A novel rice constitutive promoter named PSUI1 with 1 941 bp was isolated using the genomic DNA of the indica rice variety Minghui63 based on a PCR method.To determine the expression strength and pattern of the novel constitutive promoter,the cloned promoter was fused with the β-glucuronidase (GUS) reporter gene to form plant expression vector DX2181b-PSUI1,and the maize ubiquitin promoter was also fused with GUS reporter gene to form expression vector DX2181b-PUbi as the control.Both DX2181b-PSUI1 and DX2181b-PUbi were transformed into japonica rice variety Zhonghua11 by Agrobaeterium-mediated method.GUS staining showed that GUS gene was expessed in different rice tissues and organs at different growth stages of DX2181b-PSUI1 transgenic rice plants.Quantitative analysis of GUS activity showed that the strength of maize ubiquitin promoter was 2-3 times higher than that of the PSUI1 promoter,but the expression of PSUI1 promoter exhibited much more stable than that of maize Ubiquitin promoter between transgenic rice lines.