Objective:To construct heart-special miR-19b overexpression transgenic mouse and analyze their phenotype. Methods:Firstly,we found out the suitable restriction enzyme cutting site on the plasmid which carrying alpha-MHC promoter,and design the primers according recombination principle provided by CloneEZＲ PCR Cloning Kit. We inserted the pre-miR-19b sequence cloned from mice chromosome into the plasmid using recombinase. Secondly,after linearization of recombinant plasmid,they were injected into the embryonic stem(ES) cells. We transplanted the recombinant ES cells into the uterus of the pseudocyesis female C57BL/6J mice. At last,we selected out the lines of transgenic mouse and analyzed the phenotype of TG mouse. Results:We successfully constructed miR-19b transgenic mouse. The scores of interventricular septal thickness,left ventricle posterior wall and ejection fraction of miR-19b transgenic mouse were increased. Conclusion:The overexpression of heart-special miR-19b may lead to cardiac hypertrophy.