The invention relates to a device for preparing fuel gas and fuel oil through microalgae pyrolysis based on nontransferred arc plasmas. The device comprises a furnace body, a furnace cover, a nontransferred arc plasma generator, and a fuel oil preparation plasma gun. The furnace cover is arranged on the furnace body; the nontransferred arc plasma generator passes through the furnace cover and is arranged in the furnace body; and the fuel oil preparation plasma gun is arranged on the furnace body and is arranged under the nontransferred arc plasma generator. The device can realize pyrolysis ofthe microalgae efficiently and fully to generate fuel gas and fuel oil, thereby realizing efficient conversion of biology-fuel; and heat and waste heat in the plasmas are utilized to heat water vapor,so that electrical energy is utilized effectively, energy consumption is reduced, and cost is reduced.