Recently, medium Mn steels (MMnS) have been extensively investigated because of the excellent mechanical combination of strength and ductility achieved at the relatively low alloying cost. Intercritical annealing (IA) is a key process of MMnS to form intercritical austenite that can be retained fully or partially at room temperature, which can trigger transformation-induced plasticity and then improve work hardening during deformation. However, this process leads to a relatively low yield strength because the recovery, recrystallization, grain growth, coarsening, and dissolution of precipitates could occur during IA. In this study, the microstructural evolution and resultant mechanical properties of Cu-V dual alloyed 3Mn steel were examined during two manufacturing processes: hot rolling → warm rolling at 550-650°C → IA at 690°C for 10 min (termed as WR-IA) and hot rolling → aging at 550-650°C for 70 min → IA at 690°C for 10 min (termed as Aging-IA). That is,the two processes differentiate in either the warm rolling or the aging process used as the intermediate process. WR-IA specimens exhibit significantly higher ductility than Aging-IA ones, but they both have the same yield strength. The former is attributed to a large quantity of defects introduced during warm rolling, which promoted austenite reverse transformation during IA and led to a large fraction of retained austenite. The resultant tensile properties include yield strength of 1230-1320 MPa and ductility of 23%-29%, which is superior to those of either V- or Cu-alloyed MMnS published in references. In particular, higher yield strength was achieved because the dual alloying of Cu-V and the two-stage thermomechanical process, that is,warm rolling plus IA, are adopted. The first warm rolling promoted Cu-rich precipitates dispersed for strengthening, and the precipitation of VC during subsequent IA could compensate for the softening caused by IA. Consequently, a high yield strength was achieved. Meanwhile, 25%-30% fraction of austenite was retained, thereby providing transformation-induced plasticity during deformation, leading to high ductility.