Biochar has a well-developed pore structure and a large number of functional groups and negative charges on its surface, so it has a strong adsorption and fixation ability for heavy metal ions. It can enhance the complexing ability of soil to heavy metal cadmium by changing the physical and chemical properties of upper soil, effectively reduce cadmium pollution in soil and alleviate the toxic effect of heavy metals on crop growth. It has a broad application prospect in controlling and treating soil cadmium pollution. Aiming at the problems existing in current research, the structures of herbaceous biochar, woody biochar and activated carbon and their adsorption differences for polar and nonpolar substances were systematically studied, and the adsorption properties and characterization parameters of different carbon materials were explored. By exploring the passivation system of high cadmium plants such as rice and rape with biochar as the core. The remediation effect of biochar on cadmium contaminated soil was explored, and the previous research results were applied to the reclamation and remediation of copper tailings. Intelligent on-line monitoring system of soil environmental parameters is adopted to monitor the changes of soil temperature, humidity and pH value in real time, so as to realize the informatization of remediation process and provide scientific basis for the application of biochar in soil cadmium pollution control. The main results are as follows: (1) Due to the influence of carbonization temperature and raw materials, the specific surface areas of three kinds of carbons are: coconut shell activated carbon (AC-Y) >; Woody seabuckthorn biochar (BC-M) >: herbaceous straw biochar (BC-C); Number of basic functional groups: AC-Y & gt；; BC-C & gt； BC-M, basic functional group density: AC-Y & gt；; BC-M & gt； BC-BC; Number of acidic functional groups: BC-C & gt；; AC-Y & gt； BC-M, the density of acidic functional groups BC-OBC-m >; AC-Y, total functional group density BC-OAC-y >; BC-M. AC-Y is nonpolar, and it has the strongest adsorption capacity for nonpolar organic matter Phe. After 6 hours, the adsorption rate of Phe is as high as 94.40%. BC-C and BC-M are polar, and they have strong adsorption capacity for polar Cd2+ in solution. It is more accurate to characterize "polar carbon" and "nonpolar carbon" and the strength of carbon polarity by the density of acid-base functional groups than by the number of acid-base functional groups. (2) The isothermal adsorption curve of Cd2+on three kinds of activated carbon accords with Freundlich multilayer adsorption model, and the adsorption process accords with quasi-second-order kinetic equation. At 25℃, the saturated adsorption capacities of BC-M, BC-C and AC-Y for Cd2+ are 7.89mg/g, 7. 12mg/g and 6.8 1mg/g respectively. Considering the factors such as specific surface area, number of functional groups, density and pore size distribution, and focusing on the stability of Cd2+ adsorption by biochar, BC-M is more suitable for the treatment of heavy metal cadmium pollution in soil than BC-C.. (3) Adding biochar to soil polluted by cadmium for a long time will increase the content of available cadmium in soil in a short time, thus "activating" cadmium in soil; Under the long-term action, biochar plays a "passive" role in soil cadmium. The passivation system with biochar as the core has played an obvious role in the treatment of soil cadmium pollution. The combined system of 1% biochar and passivator IB-CSSH (5 times the molar mass of total cadmium in soil) has superimposed effect on cadmium passivation. Adding biochar to stabilize for 3 days, and then adding B-CSSH has the best passivation effect. Compared with the control group, after 120d, available cadmium content in SD-H soil decreased by 83.93%, residual cadmium content increased by 78.62%, available cadmium content decreased by 68.89% and residual cadmium content increased by 58.97%. (4) Black soil system has a good effect on inhibiting cadmium absorption by oilseed vegetables. Compared with the control group, the cadmium enrichment coefficient of lettuce in YMC 1 soil decreased by 57.35% on the 50th day. Different addition ratios of black soil system have different effects on inhibiting cadmium absorption by oil wheat vegetables. Adding 2% black soil system to YMC- 1 soil, the cadmium accumulation of oil wheat vegetables decreased by 55.09% compared with the control group at 70 days. Adding 2% black soil system to YMC-H soil, the cadmium content of edible parts of oil wheat vegetables decreased by 22.45% within 70 days. At different growth stages of oilseed vegetables, the extraction amount of available cadmium by 0. 1mol/L HAc was higher than that by 1mol/L NH4Ac and 0.0 1mol/L CaCl2, and the correlation coefficients R2 between the available cadmium content in soil extracted by three extractants and the enrichment amount of oilseed vegetables were 0.6308 and 0.308, respectively.