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The research utilizes the constant strain rate method to systematically investigate the superplastic behavior of fine-grained TC4 alloy sheets under temperature conditions of 880-920 °C and strain rate conditions of 0.0005 s-1-0.005 s-1. Furthermore, the study encompasses a comprehensive analysis characterizing the microstructural evolution during the superplastic deformation. This study reveals that with the elevation of superplastic deformation temperature, the alloy consistently undergoes conspicuous dynamic recrystallization. This phenomenon results the transformation in the superplastic deformation mechanisms of the alloy. At 880°C with a strain rate of 0.001 s-1, the alloy exhibits a cooperative superplastic deformation mechanism involving grain boundary sliding, grain rotation and sliding. Under these conditions, TC4 alloy achieves an elongation of up to 1039%, accompanied by a notable strain sensitivity coefficient (m-value) of 0.51. In contrast, at 920°C with a strain rate of 0.001 s-1, the alloy"s superplasticity predominantly relies on grain boundary sliding and intragranular dislocation glide, resulting in a diminished elongation of 746% and a reduced m-value of 0.39. These research findings elucidate the critical factors behind the varying superplastic performance of TC4 alloy across distinct temperature and strain rate conditions，which is significant to further study the complex mechanical behavior and deformation mechanism of TC4 titanium alloy during superplastic deformation.