Ultrathin crystalline silicon wafers for photovoltaic applications have attracted intensive attention because of potential benefits in cost-effectiveness. Structural design with high light absorption is important for photovoltaics because planar ultrathin silicon is poor in absorption. We conduct a comparative investigation on designs of light absorption enhancement for -thick ultrathin crystalline silicon, where the front texture is a nanopyramidal structure and the rear adopts several designs. Our calculation results show that both of the ultrathin silicon with front nanopyramids and rear silver nanoarrays and the ultrathin silicon with two-sided nanopyramids are promising for photovoltaic applications. For the latter design, the calculated photocurrent achieves the highest value of when a perfect electric conductor layer is applied at the bottom. In contrast, the former design has a lower photocurrent value of . But, this design is of practical significance because the majority of experimental reports on ultrathin crystalline silicon solar cells are single-sided front-textured at present and the fabrication techniques of plasmonic Ag nanoarrays are matured. Compared with previous reports, the present work offers a multiple option of structural designs for ultrathin crystalline silicon to enhance the light absorption for photovoltaic applications.