Taking the radish cultivar‘Baiyuchun’as material，this paper gained coded sequence of aquaporin gene RsAQP1b by homology-based cloning method；and analyzed the expression pattern of RsAQP1b gene and protein under drought stress during radish seedling period，and studied the expression of this gene in tobacco，changes in MDA content and activity of protective enzyme under drought stress. The results indicated that CDS of RsAQP1b was 861 bp，encoding a protein of 286 amino acids. Polyclonal antibody of RsAQP1b was prepared and its titer was over 1∶512 000. Real time PCR and western blot detection showed that the expression level of RsAQP1b gene and protein was down-regulated by drought stress. Under PEG6000 drought stress treatment，the MDA content in transgenic and wild type（WT）tobacco was all increased，but the increasing rage of transgenic tobacco was small. The content of SOD in transgenic RsAQP1b tobacco showed an increasing tendency，while the CAT content showed a tendency of first rising then declining. The POD content showed an increasing tendency. The enzymatic activity was all exceeded that of the relevant CK of wide type.