Abstract: In this work,the coding region of Asp was amplified by PCR from the genomic DNA of the Monascus and the homologous vector p BC- Hygro- Asp was constructed and then was introduced into the Agrobactium tumefaciens strain GV3101 for further study. The agrobacterial cells harboring the p BC- Hygro- Asp vector was introduced into the genome of Monascus via Agrobacterium tumefaciens- mediated method and the positive recombinant of Monascus was obtained. The expression level of acid protease gene in transformants strain was3.30 times that of the wild Monascus,which indicated that the Monascus recombinant with high yield of acid protease was successfully achieved. The gene sequence of acid protease showed the gene had two aspartic proteases with active sites and the protease was a hydrophilic secretory protein without performance of signal transduction and keet the same evolution rate as that of Aspergillus ruber.