The electrochemical treatment of COD contained in biologically pretreated coking wastewater treated by a three-dimensional electrode system with modified coke as the particle electrode was investigated.And the electrochemical perfomance of the coke modified with various active components was studied.The results show that the coke modified with Fe(NO3)2 has the lowest energy consumption and higher COD removal rate under the same condition,and the modified coke has better surface characteristics for the purpose of this study.In addition,the kinetic constant was also calculated.The study shows that the three-dimensional electrode system with Fe(NO3)2-modified coke can give a satisfactory solution in biologically pretreated coking wastewater.