By applying nonequilibrium Green's functions in combination with density-function theory, the spin-dependent transport properties of a single-molecule electric revolving door-based spintronic device are investigated. The computational results show that magnetoresistance ratios are strongly dependent on the door states of the single-molecule electric revolving door. Under the application of a gate electric field, the single-molecule electric revolving door can be changed from the closed-door state to the open-door state, and thus the maximum magnetoresistance ratio of the corresponding spintron...