Abstract: The microstructure of as-cast and hot-rolled δ-TRIP steel Fe-0.4C-10Mn-6Al were studied by OM, SEM,EBSD and XRD techniques, and the tensile tests of the experimental steel s were carried out. The microstructure and mechanical properties of the test steel in as-cast and hot-rolled state were obtained by analysis. The results show that the structure of δ-TRIP steel Fe-0.4C-10Mn-6Al in as-cast and hot-rolled states is mainly δ ferrite and austenite, and the hot-rolled state also contains a small amount of carbides. The average grain size in as-cast state is 20.08 μm, and the average grain size in hot-rolled state is smaller than that in as-cast state, which is 3.17 μm. Compared with those of the as-cast state, the strength and elongation of the hot-rolled steel are improved, and the comprehensive mechanical properties are greatly improved.