Abstract: N, P and S multi-doped activated carbon was prepared from sunflower straw by the synergistic activation of KOH and thiourea with its own phosphorus element as phosphorus source, thiourea as nitrogen source and sulfur source. The effect of activation temperature on the adsorption performance of doped activated carbon was discussed. The pore structure and surface chemical properties of doped activated carbon were analyzed by nitrogen adsorption desorption isotherm and X-ray photoelectron spectroscopy(XPS); the electrochemical performance of doped activated carbon as electrode material for supercapacitor was investigate by galvanostatic dharge discharge(GCD) and cyclic voltammetry(CV). The results showed that as the increase of activation temperature, the iodine adsorption value of doped activated carbon increased first and then decreased; when the activation temperature was 900℃, the iodine adsorption value reached the maximum(2 080 mg/g). The synergistic activation of alkali and thiourea was beneficial to enhance the specific surface area and total pore volume of doped activated carbon, the specific surface area and total pore volume of doped activated carbon P, T-900, which was obtained under activation temperature 900℃, were 2 517 m²/g and 1.73 cm³/g, respectively. The doped activated carbon P, T-900 contained nitrogen(N), phosphorus(P) and sulfur(S) elements, and their mass fractions were 1.9%, 0.52% and 2.46% respectively. When the current density was 1 A/g, the specific capacitance of P, T-900 reached 259 F/g in 6 mol/L KOH electrolyte. When the current density was 10 A/g, the specific capacitance of P, T-900 reached 230 F/g, and the initial capacitance retention was as high as 88.8%.