Temperature reverting rolling process (TRRP) is a newly developed technology for producing heavy steel plate with ultrafine grained surface layer. With hybrid structures along thickness direction, TRRP steel plate has excellent fracture toughness with crack arrestability which arouses interest recently. However, the crack arrest mechanism of the surface layer is still unclear to date. In this work, two types of steel plate produced by TRRP and traditional thermo mechanical control process (TMCP) were studied in order to get a comprehensive understanding of the crack arrest mechanism. The mechanical property tests demonstrate that the toughness of surface layer of TRRP steel is significantly higher than that of TMCP steel, while the mechanical properties at 1/4 thickness position of the two types are quite close. It's worth noting that ductile-brittle transition temperature of the TRRP steel surface layer is as low as -100 ℃. Microstructure analysis of the TRRP surface layer shows a coexistence of equiaxed ferrite grains with grain sizes of about 2 μm and dispersed M-A constituent. Numerical simulation of the temperature field of TRRP intermediate slab reveals the microstructure forming process. First, the surface layer is cooled lower than phase transformation temperature, which results in the generation of bainite ferrite. Subsequently, dynamic recrystallization of ferrite takes place in rolling process and leads to the formation of ultrafine grains. Instrumental impact test at -60 ℃ shows that the crack propagation of TRRP steel is effectively inhibited after a steady developing stage. The morphological analysis of the cross section of fracture shows significant plastic deformation in the surface layer, which means crack propagation energy is absorbed. As a result, the crack propagation is efficiently arrested. The statistical study of the grain orientations in the surface layer of TRRP steel indicates a randomly distribution of the ultrafine grains, which can hinder the crack propagation effectively. The nano indentation test shows that the hardness distributions of TRRP steel are mainly below 2.0 GPa. This means the microstructure is characterized by a small amount of hard phase dispersing in soft matrix, thus the crack initiated at the interface of phases can hardly propagate.