Abstract: The coupling effects of the metastable austenitic phase and the amorphous matrix in a transformation-induced plasticity (TRIP)-reinforced bulk metallic glass (BMG) composite under compressive loading were investigated by employing the digital image correlation (DIC) technique. The evolution of local strain field in the crystalline phase and the amorphous matrix was directly monitored, and the contribution from the phase transformation of the metastable austenitic phase was revealed. Local shear strain was found to be effectively consumed by the displacive phase transformation of the metastable austenitic phase, which relaxed the local strain/stress concentration at the interface and thus greatly enhanced the plasticity of the TRIP-reinforced BMG composites. Our current study sheds light on in-depth understanding of the underlying deformation mechanism and the interplay between the amorphous matrix and the metastable crystalline phase during deformation, which is helpful for design of advanced BMG composites with further improved properties.