The rapid urbanization and industrialization in China have led to an urgent dilemma for controlling urban air pollution, including the intensified emission of gasoline vapor into the atmosphere. Herein, we selected highland barley straw as a raw material and KOH and tetramethylammonium hydroxide (TMAOH) as activators to synthesize nitrogen-doped layered porous carbon (K-thAC) by a three-step activation method. The obtained K-thAC materials had a high specific surface area, reaching 3119 m2/g. Dynamic adsorption experiments demonstrated a superior adsorption capacity of up to 501 mg/g (K-thAC-25) for gasoline vapor compared with other documented carbon adsorbents. Moreover, adjusting the ratio of raw materials with a series of active ingredients could further improve the pore properties of the obtained K-thACs and their adsorption performance for gasoline vapor. Furthermore, the K-thAC materials were also characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), synchronous thermogravimetry (STA), X-ray powder diffraction (XRD), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption tests. This study synthesized a novel plant-based material to treat gasoline vapor pollution efficiently.