Alginate sponges have been widely studied in areas of wound healing, drug release, tissue engineering, and wastewater treatment due to their potential biological activity, biocompatibility, high porosity, and large surface area. However, their poor mechanical properties greatly limit the practical applications of alginate sponge. In this study, a structurally controllable and high-performance sponge material preparation strategy was proposed by optimizing the structure of the freeze-dried calcium alginate (CA) sponge using fluffy and porous thermally bonded nonwovens (NWs). The performance of composite sponges (CA@NWs) prepared at different pre-freezing temperatures and concentrations were tested. The results showed that the NWs skeleton could improve the formation structure and size stability of the freeze-dried CA sponge, making it have good fluid absorption, moisture permeability, moisture retention, and wet state mechanical properties. The RF-1.0-CA@NWs sponge had the highest fluid absorption rate of 1415 %. The wet state RF-1.5-CA@NWs sponge had tensile strengths of 1.913 MPa and 0.465 MPa in the MD and CD directions, respectively, which was about 95 times higher than that of the wet state pure CA sponge.