Sixteen 3,5-dimethylorsellinic acid-based (DMOA-based) meroterpenoids, including 10 new compounds, asperterpenes D-M (1-10), were obtained from Aspergillus terreus. The structures and absolute configurations of the new compounds were confirmed by extensive spectroscopy, single-crystal X-ray diffraction analysis, and experimental electronic circular dichroism (ECD) measurements. Compounds 2, 3, and 7 are the first 3,5-dimethylorsellinic acid-based meroterpenoids possessing a unique cis-fused A/B ring system. These new compounds were evaluated for their inhibitory activity against β-site amyloid precursor protein-cleaving enzyme 1 (BACE1). Compounds 2, 3, and 7, the first 3,5-dimethylorsellinic acid-based meroterpenoids possessing cis-fused A/B rings, exhibited significant inhibitory activities against BACE1 with IC50 values of 3.3, 5.9, and 31.7 μM, respectively.