BACKGROUND:: Differentiated embryo-chondrocyte expressed gene 1 (DEC1) is a basic helix-loop-helix transcription factor, which is closely associated with some malignant cancers. OBJECTIVE:: To construct small interfering RNA (siRNA) expression plasmid target to DEC1. METHODS:: The mRNA sequence of DEC1 gene was searched from NCBI. Utilize of Katahdin siRNA technology, DEC1-SIRNA oligonucletides were inserted into pGreenPuro™ shRNA Cloning and Expression Lentivector, after annealing, then transformed into JM-109. The recombinant plasmid was identified by Agarose gel electrophoresis analysis, ultraviolet spectrophotometer analysis, PCR and DNA sequencing. RESULTS AND CONCLUSION:: The recombinant plasmid pGreenPuro™ shRNA Cloning and Expression Lentivector-DEC1 was obtained by connecting 25 bp segment containing DEC1 sequence to pGreenPuro™ shRNA Cloning and Expression Lentivector. Agarose gel electrophorsis analysis and ultraviolet spectrophotometer analysis confirmed that plasmid DNA had higher purity. DNA sequencing showed Targeting siRNA oligonucleotides were correctly inserted into the eukaryotic expression vector pGreenPuro™ shRNA Cloning and Expression Lentivector without base mutation. The interference vector pGreenPuro™ shRNA cloning and expression lentivector-DEC1 was successfully constructed.