The influence of soaking temperature on microstructure of high temperature multi-pass compression deformation for two low carbon steels (steel A: w C = 0.032% and wMn = 0.25%; steel B: w C = 0.165% and wMn = 0.38%) is studied on the thermal-mechanical simulator in order to rationalize the hot-rolling schedule of low-carbon steel and to promote the low-temperature heating technology. The results show that the microstructures of steel A are almost not affected by reducing soaking temperature, but the acicular ferrite forms in steel B when the soaking temperature is reduced from 1 200 to 1 170?, due to its smaller initial austenite grain size according to recrystallization kinetics theory. © Shanghai Jiaotong University and Springer-Verlag Berlin Heidelberg 2011.