The objective of the current study is to introduce a coupled thermo-mechanical phase field model to elucidate shear ductile fracture under varying strain rates and temperatures. Both the plastic work threshold and fracture energy exhibit dependence on the strain rate and temperature. To explore this in detail, hat-shaped specimens are adopted to systematically investigate shear ductile fracture under distinct strain rates and temperatures by the split Hopkinson pressure bar apparatus. The simulated and experimental strain waveforms are then compared to calibrate and validate the damage parameters of the presented phase field model. The results demonstrate that the numerical simulations are in agreement with the experiments. Moreover, the fracture process of the hat-shaped specimen is also examined. The numerical results furnish a reliable description of the hat-shaped specimen from damage initiation to complete fracture. It's found that the influences of strain rate on shear stress and fracture initiation are less pronounced than that of temperature for U75V steel. In summary, the developed phase field model can reproduce shear ductile failure of the hat-shaped specimen under diverse strain rates and temperatures.