Passenger vehicle torque reactor were manufactured by die-casting and ADC3 alloy, fracture occurred after sale in the same position and form. In order to find out the reason of fracture, fracture analysis, chemical composition analysis and microstructure analysis were carried out on the broken torque reactor, and then the mechanical properties of the same batch of torsion bar were analyzed and examined. The results show that the fracture of the torque reactor belongs to brittle fracture, the crack originates near the stress groove in the middle of the tension bracket, the composition of the torque reactor meets the standard requirements, and the microstructure is normal. However, the actual mechanical properties of ADC3 alloy of the same batch of torque reactor are lower than the design requirements. The comprehensive analysis shows that the root cause of the fracture of the torsional tie rod is the lack of real strength of the material and the secondary cause is the internal casting defects. Considering various factors, it is concluded that under the condition of not changing the structure and design of the torque reactor, ZL111 alloy is adopted for forming the torsion bar by recast. The torque reactor meets the actual requirements and achieves good results.