Mn12Ni2MoTi（Al） steels were fabricated by cold rolling with total reductions of 65% and 80%, respectively, and subsequently annealed at 745 ℃ for different times. The microstructures and mechanical properties of samples were investigated using X-ray diffraction（XRD）， scanning electron microscope（SEM）， transmission electron microscope（TEM）， and hardness and tensile tests. The nucleation and coarsening kinetics of Laves phase as well as its influence on grain refinement were also examined. The results show that the fine（Fe，Mn）2（Mo，Ti） Laves phases with hexagonal structure have precipitated during annealing for 5 min. With the increase of annealing time， the Laves particles gradually grow.The volume fraction of Laves particles increases rapidly in the first hour of annealing， and then slowly increases to the maximum value at 8 h. Afterwards，the volume fraction of Laves particles almost keeps unchanged. The Laves phases firstly precipitate at grain boundary，and then pin the grain boundary. The pinning pressure of Laves phase particles first increases and then decreases with the annealing time. When the annealing time is 4 h，the pinning pressure reaches the maximum value. Besides，the larger pre-deformation of cold rolled samples results in the higher coarsening rate of Laves phases. At the same annealing condition， the larger pre-deformation of samples leads to the smaller pinning pressure of Laves phases. Although the long-time annealing or large pre-deformation makes the pinning pressure provided by Laves phase particles to be small， Laves phase particles still can effectively pin the grain boundaries， which greatly improve the thermal stability of the recrystallization grain. For the 65% CR sample， the recrystallization grain still remains at sub-micron level after annealing for 8 h. The Mn12Ni2MoTi（Al） duplex steel with submicron recrystallization grain has both high yield strength and good elongation， which is much higher than that of quenched martensitic samples.