Based on the analysis and characterization of complex cyanide in biochemical tail water of coking wastewater,the harmless treatment of complex cyanide by "Fenton+coordinated aeration+coagulation precipitation" technology was studied through single factor experiment,and the content of complex cyanide in the effluent of clear pool was taken as the index.The test results showed that the optimized process control index of this technology was as follows:The pH was 3~3.5,the mass ratio of ferrous sulfate to wastewater was 0.005︰1,the mass ratio of hydrogen peroxide to wastewater was 0.01︰1,the aeration rate was 16~18 m3·m-3,and the cyanide mass concentration of the treated wastewater was less than 0.02 mg·L-1,meeting the relevant requirements of GB 16171—2012.