Abstract: Abstract　Objective　Clone the human fragile X mental retardation gene 1 cDNA into the pET22b(+) vector, express and purify FMRP to study its function. Methods　The plasmid pET22b(+)-FMR1, constructed by molecular cloning, was transformed into E. coli BL21(DE3) competent cells and induced to express FMRP by IPTG. Then, FMRP was purified by affinity chromatography. Purified FMRP was tested for its RNA binding ability. Results　FMR1 cDNA was successfully cloned into pET22b(+) vector and expressed in E. coli BL21(DE3). A protein with Mr 69 000 was purified and confirmed to be FMRP by western-blot. This protein retained the RNA binding ability of FMRP. Conclusion　FMR1 gene was successfully expressed in BL21(DE3) cells, and highly purified FMRP with RNA binding ability was obtained, which provided reliable material to study the function of FMRP.