The invention discloses an ethylbenzene reactor environment-friendly purging device and an ethylbenzene reactor environment-friendly purging method. The ethylbenzene reactor environment-friendly purging device comprises a reactor, an active carbon tower, a heater, a first valve, a second valve, a third valve, a fourth valve and a fifth valve, wherein the inlet of the first valve is communicated tothe outlet of the heater, the outlet of the first valve is communicated to the inlet of the reactor, the outlet of the second valve is communicated to the outlet of the first valve, the inlets of thethird valve, the fourth valve and the fifth valve are communicated to the outlet of the reactor, the outlet of the fourth valve is communicated to the inlet of the active carbon tower, the outlets ofthe active carbon tower and the fifth valve are communicated to atmosphere, and the active carbon tower is filled with flame-retardant active carbon. According to the invention, heated nitrogen maintains the activity of the active carbon tower, and after the temperatures of each bed layer in the reactor are reduced to a certain value, purified wind is introduced to oxidize the ferrous sulfide inthe reactor into iron sulfide, and the gas inlet amounts of the nitrogen and the purified wind are adjusted according to the temperature rise speed in the reactor, so that the risk generated in the purging process is reduced.