Mg and Mg-based alloys are distinguished by their high specific strength-to-density ratios but demonstrate low strengths at ambient to elevated temperatures. Producing Mg-based composites offers an effective means of strengthening Mg. Nevertheless, the mechanical properties of Mg-based composites are primarily dependent on their architectures. Here, bioinspired Mg-based composites with fish-scale-like orthogonal plywood and double-twisted Bouligand-type (i.e., double-Bouligand) architectures were fabricated by the pressureless infiltration of an Mg melt into the woven contextures of stainless steel fibers. The phase constitution, microstructure, and tensile properties of the composites at room temperature and 200^oC were compared with a composite where stainless steel fibers were randomly oriented in-plane. The relationships between the microstructure and mechanical properties were also explored. The results showed that the stainless steel fibers played a notable role in strengthening the composites and were pulled out from the Mg matrix to promote plastic deformation and energy consumption. The mechanical properties of the composites were closely associated with their microstructures, with fish-scale-like architectures displaying higher strengths and larger plasticity than the randomly oriented ones. In particular, the double-Bouligand architecture allowed coordinated deformation between the fibers of different orientations and promoted crack deflection along the fibers, thereby alleviating the localization of deformation and damage in the composite. Therefore, it bestowed larger plasticity at room temperature and higher tensile strength at high temperature. By exploiting new bioinspired architectures, this study provides guidance for optimizing the architectural design of Mg-based composites to improve their mechanical properties.