Recently, biochar, prepared through incomplete combustion or pyrolysis of crop straws, has been a hot spot in the research of agriculture and environment. Amendment of biochar into the soil may help sequestrate C, reduce emission of greenhouse gas, improve soil fertility and hence crop yield. Besidess, biochar has a relatively high specific surface area, well-developed pore structure and abundant surface functional groups. Chlorobenzenes (CBs) are a typical kind of chlorinated hydrophobic organic pollutants and widely used in many industries, such as dye, pharmacy, pesticide and organic synthesis. China is a major producer of CBs in the world. As a result of their extensive application, CBs have been detected in soil, vegetable, water body and various environmental media, in China, posing a great potential risk to the environment. Remedying CBs contaminated environment has attracted wide concerns. Although some progresses have made in the study on biochar adsorbing hydrophobic organic contaminants, little has been reported about biochar adsorbing high chlorinated benzene. Elucidation of the process and mechanism of biochar adsorbing CBs will help readers better understand interactions between biochar and hydrophobic organic pollutants, and use biochar scientifically in environmental remediation. In this study, straw was used as raw material biochars and pyrolyzed under three different temperatures (400℃, 500℃ and 600℃) into three different kinds of biochar, which were marked as WSB400, WSB500 and WSB600, respectively. Elemental compositions of the biochars were determined using an element analyzer, their specific surface areas measured using the BET method; their surface functional groups analyzed using a Fourier transform infrared spectrometer, and their surface morphological features characterized using a scanning electron microscope. And kinetics and isotherms of biochar adsorbing pentachlorobenzene (PeCB) and hexachlorobenzene (HCB) were explored using the batch equilibration method. Results show that organic components in wheat straw were carbonized during the pyrolytic process, and their carbonization degree increased, but O/C, (O+N)/C and H/C of the biochars decreased with the temperature rising from 400℃, 500℃ to 600℃, indicating that the wheat straw based biochar decreased in hydrophilicity and polarity, but increased in aromaticity with the rising pyrolytic temperature. Higher pyrolytic temperature depleted surface polar functional groups in the biochar. The three different kinds of wheat straw biochars were all able to adsorb CBs in water quickly and efficiently. The sorption process could be divided into two phases: rapid sorption process and subsequent slow sorption and equilibrating process. It took about 48 hours for the sorption to reach equilibrium. The biochars adsorbed HCB faster than it did PeCB and the pseudo-second-order kinetic equation could be used to better describe the sorption process. CBs adsorption did not affect much FTIR spectra of the three kinds of biochars sorbing, indicating that the sorption was dominated with physical sorption. In terms of CBs saturated sorption quantity, the three kinds of biochars followed an order of WSB400 ＞ WSB500 ＞ WSB600. With the rising pyrolytic temperature, the adsorption of PeCB and HCB on the biochars became more and more nonlinear. The adsorption of PeCB and HCB displayed an apparent linear isotherm on WSB400, but concave non-linear curves on WSB500 and WSB600. A linear isotherm signifies presence of partition, while a nonlinear isotherm that of surface adsorption. The analysis of contributions of partition and surface adsorption to total sorption of CBs on wheat straw biochar reveals that higher temperature in biochar preparation turns the sorption mechanism from partition dominated into partition-surface adsorption co-dominated one.