718 alloys have become key materials in nuclear power and aerospace fields because of their excellent mechanical properties and good high-temperature processing performance. Nuclear grade 718 alloys need to meet special requirements such as strong irradiation resistance and small thermal neutron absorption cross-section, therefore, the elemental content of Ni, Nb, and C in alloys is generally controlled at low levels, however, there is less research on the thermal deformation structures and properties of such low Ni, Nb, and C nuclear grade 718 alloys. This work investigated the effects of different hot rolling process parameters and post-rolling heat treatment on the structures and tensile properties of nuclear grade 718 alloys by designing different initial rolling temperatures and deformation amounts. The results show that, under the condition that the initial rolling temperature is below 1150℃ and the heat deformation is lower than 90%, a large number of elongated grains appear in the structure and the elongation of the alloy is reduced; when the initial rolling temperature achieves 1150℃ or the heat deformation reaches 90%, a uniform equiaxed grain structure can be obtained. After the solid solution treatment of the rolled plate at 990℃, δ phases are precipitated and pinned to grain boundaries, forming a mixed grain microstructure, as well as the average values of yield and tensile strength at 315°C after standard aging treatment can reach 1050MPa and 1238MPa, accompanied by an elongation after the fracture as high as 26%; Upon solid solution treatment at 1020°C, the grown equiaxed grains are obtained, whereas the average yield and tensile strength at 315°C can attain 985MPa and 1175MPa after standard aging treatment, respectively, and the elongation after the break is up to 29%, showing good strength and toughness.