The whole designed gene expressing a peptide consisting of calcitonin gene-related peptide (CGRP) (37aa) itself, a signal peptide at its N terminus and an amidated site at its C terminus is cloned into mammalian expression vector pBPV. The pBPV-CGRP plasmid DNA is directly injected into the spontaneous hypertension rats (SHR) and results in the significant decrease of SHR's blood pressure during 3～22 days after injection. The percent of decrease reaches more than 12%, even up to the top 24.42% on the 16th day. The effect can last for longer time and also be better than that of CGRP protein.