Abstract: Aspergillus niger Ja was cultured in three different isolation mediums, and the growth of these colonies were observed separately. The enzymatic activity of polygalacturonic acid enzyme was compared qualitatively by measuring Dp/Dc of transparent circles, and bromophenol blue medium was chosen as a better isolation medium. A high-yield polygalacturonic acid enzyme strain, AspT7, was selected from natural soil through enrichment culture, acclimating, bromophenol blue medium screening and shake flask rescreening. Its enzyme activity of polygalacturonase-producing reached 65000 U/mL. It was preliminary identified as Aspergillus niger, and named as Aspergillus niger AspT7.