For thermo-mechanical treated 2197 alloy of various states, effects of thermo-mechanical treatment on the mechanical properties and microstructure of 2197 alloy are studied through analyzing the mechanical properties in tensile tests and observing the microstructures by TEM observation. Results show that the dominating precipitated phase of peak-aged 2197 alloy during thermo-mechanical treatment is T1 phase，the size of which is 50~150 nm. The precipitation and growth of T1 phase are accelerated due to the excellent nucleation sites of heterogeneous nucleation for T1 phase offered by thermo-mechanical treatment，therefore，the time for 2197 alloy to reach the peak-aged state is shortened. The strength of 2197 alloy for peak-aged state is increased through thermo-mechanical treatment because the strengthening effect of T1 phase with higher aspect ratio is bigger than that of δ′ and θ′ phases.