In this study, a capacitorless one-transistor dynamic random-access memory (1T-DRAM) based on a polycrystalline silicon metal-oxide-semiconductor field-effect transistor with a separated channel layer and a fin-shaped storage layer was proposed and analyzed. The memory performance is improved by a fin-shaped storage layer and a region separated into a channel layer and a storage layer. The proposed 1T-DRAM achieved the high sensing margin of 19.09 μA/μm and the long retention time of 525 ms at T = 358 K.