Abstract: The grain size and grain boundary characteristics of Fe-18Mn-3Si-3Al TWIP steel at different annealing temperatures were studied by EBSD method. The results show that, the effect of annealing temperature on grain size is obvious. When the annealing temperature is lower than 1050 ℃, the grain distribution is more uniform, and the grain size is concentrated in a smaller size range.However, when the annealing temperature exceeds 1050 ℃, the grain size is concentrated in 15-35 μm, and the size span is large.With the increase of annealing temperature, the variation trend of Σ3 grain boundary and total CSL grain boundary ratio is the same, which is first increasing then decreasing. The peak value is obtained at annealing temperature of 950 ℃.The formation of twins is closely related to grain orientation, and most twins tend to form in grains with < 111> orientation.