Biochar is a carbon-rich material produced by pyrolyzing biomass in the absence of oxygen. Due to the presence of well-developed micro-pores and high specific surface area, biochar displays an excellent sorption capacity and hence is deemed as green environmental sorbent and has been extensively used in the field of agriculture and environment. Polycyclic aromatic hydrocarbons (PAHs) are a typical kind of persistent hydrophobic organic pollutants commonly found in soil and sediments. Thanks to the high affinity of sorbents to PAHs, sorption has become a critical process governing the fate and transport of PAHs in the environment. An experiment was carried out using biochars prepared through pyrolyzing corn stalks under different temperatures, to explore kinetics of the biochar sorbing naphthalene, a volatile organic compound in the PAHs family, and effect of dosage of biochar on the kinetics. So far, reports have been available demonstrating that sorption kinetics is a useful tool to explain the mechanism of naphthalene sorption. It is, therefore, essential to have a better understanding of the mechanism of biochar sorbing naphthalene and select an optimal sorbent, through studying effects of pyrolysis temperatures and dosage of corn-stalk-derived biochar on sorption kinetics of naphthalene. The experiment was designed to use the batch processing method. Out of each of the four kinds of biochars, C300, C400 ,C500 and C600, prepared under 300°C, 400°C, 500°C and 600°C, respectively, in pyrolysis, two portions, 10 mg and 50 mg each, were taken and put into flasks separately. Into each flask, 10 mL of CaCl2 solution containing 25 mg L-1 naphthalene was added. A soil ion environment was simulated with 0.01 mol L-1CaCl2 solution as background solution. The mixture was shaken at 30±2 °C and 120 rpm for 10 min, 1, 4, 6, 12, 24 and 48 h, separately, in dark and then sampled. Fitting analysis of the kinetic data was performed with the pseudo-first-order kinetic model, the pseudo-second-order kinetic model, the intraparticle diffusion model and Boyd model to elucidate the mechanism of biochar sorbing naphthalene. Results show that Naphthalene sorption capacity at equilibrium (qe) of biochars of the same kind varied with dosage in an order of 10 mg >50 mg, but qe of biochars the same in the dosage did with pyrolysis temperature in an order of C400>C300>C600>C500 with the dosage set at 10 mg and in an order of C300≈C400≈C600> C500 with the dosage set at 50 mg. Compared with the pseudo-first-order kinetic model, the pseudo-second-order kinetic model was much better in fitting the sorption kinetic features of the biochars regardless of dosage or pyrolysis temperature, suggesting that the sorption is related to sorbing sites in biochar, rather than simplex single-layer sorption. For biochars of the same kind, both the sorption rate constant (k) and the initial sorption rate (h) varied with dosage, and were much higher when the dosage was 50 mg than when it was 10 mg, but for biochars of different kinds, both k and h were in the order of C300≈C400≈C600>C500, regardless of dosage. Fitting analyses using the intraparticle diffusion model and the Boyd model show that the sorption process was affected by both film diffusion and intraparticle diffusion. The sorption process consists three steps: (1) film diffusion of pollutant from its transport solution to external surface of the absorbent; (2) intraparticle diffusion of pollutant during its transport inside pores of the absorbent; and (3) sorption of pollutant on the interior surface of the absorbent. The sorption process consists of two steps for biochars 10 mg in dosage and three steps for biochars 50 mg in dosage. For biochars of all kinds, it took a longer time for biochars lower-in dosage to go through the steps, which is probably because biochars higher in dosage may provide more absorbing sites. Intraparticle diffusion rate constants of biochars, regardless of kind or dosage, declined with the time going on. Biochars, C300 and C400, regardless of dosage, both had a boundary layer thicker than that C500 and C600 had, indicating the boundary layer of the former had a higher impact on the sorption. The fitting analysis using the Boyd model shows that during the naphthalene sorption process of biochars, regardless of kind and dosage, film diffusion was the rate-limiting factor. Therefore, it could be concluded that the sorption of naphthalene on corn-stalk-derived biochars was mainly governed by film diffusion of the pollutant from its transport solution to the surface of the adsorbent.