Abstract: 【OBJECTIVE】In this article we cloned the Maize Starch Branching Enzyme SBEⅡb Gene and constructed its over-expression vector successfully. 【METHOD】The total RNA extracted from Waxy corn endosperm was as template, the Coding Regions of cDNA of the Maize Starch Branching Enzyme SBEⅡb gene was amplified Utilizing the method of RT-PCR.【RESULTS】The gene was successfully amplified. Homologous Analysis result by BLAST showed that the cloned fragment has 99% identity to the sequence of the gene in GenBank. The Coding Regions of SBEⅡb gene cDNA was 2719bp in length and encode 799 amino acids. 【CONCLUSION】The cloned cDNA was ligated into the plant express-vector pCAMBIA1303 . We successfully constructed a gene over-expression vector pCASBEⅡb through GUS activity test.