The invention discloses a method for synchronously producing oil, sequestrating carbon, desulfurizing and denitrifying by utilizing microalgaes. The method for synchronously producing oil, sequestrating carbon, desulfurizing and denitrifying by utilizing the microalgaes comprises the following steps: 1, selecting species of microalgaes; 2, preparing a microalgae culture medium; 3, disinfecting a photobioreactor; 4, inoculating the microalgaes; 5, culturing the microalgaes; and 6, harvesting the microalgaes. A device for synchronously producing oil, sequestrating carbon, desulfurizing and denitrifying by utilizing the microalgaes comprises a photobioreactor, a lighting system, a temperature control system, a pH and flue gas control system, an alternating current power supply and a power supply master switch, wherein the systems cooperate with the photobioreactor. The device is specially designed for the method, and the method relies on the device. The method disclosed by the invention has the advantages that the flue gas is directly utilized for culturing oil-producing microalgaes, and microalgae oil (a raw material of microalgae biodiesel) is obtained while biological fixation of CO2 in the flue gas and removal of sulfur oxides (mainly sulfur dioxide SO2) and nitrous oxides (mainly nitric oxide NO) are realized. The device disclosed by the invention is reasonable in structure, automatically controls introduction and close of the flue gas and has high efficiency of removing CO2, SO2 and NO in the flue gas.