Isothermal compression of the Ti-6Al-4V alloy at the deformation temperatures of 950 and 980℃,height reductions of 30% and 60%,and strain rates of 0.001,0.010,0.100 and 1.000 s-1 was conducted,wherein the variations of microstructure with strain rate were investigated.The experimental results showed that the variation of the microstructure with the strain rate under one condition was significantly different from that under another condition,which meaned that the interaction between the processing parameters was great.The optimization of the strain rate under one condition was not suitable for another condition.Therefore,selecting the forging equipment and optimizing the strain rate should be based on simultaneously considering the deformation temperature and height reduction. Isothermal compression of the Ti-6Al-4V alloy at the deformation temperatures of 950 and 980 ° C, height reductions of 30% and 60%, and strain rates of 0.001, 0.010, 0.100 and 1.000 s-1 was conducted, microstructure with strain rate were investigated. the experimental results showed that the variation of the microstructure with the strain rate under one condition was significantly different from that under another condition, which meaned that the interaction between the processing parameters was great. the optimization of the strain rate under one condition was not suitable for another condition.Therefore, selecting the forging equipment and optimizing the strain rate should be based on simultaneously considering the deformation temperature and height reduction.