This invention relates to a process of preparation of substituted diphenylamine-4-diazonium salt. Said compound is an important raw material for preparing printing panel of pre-coating. After substituted benzene is reacted with potassium, it is then reacted with substituted halogen-benzene to form substituted dianil. Thereafter, the required product is obtained through nitrosation, rearrangement, reduction and diazotisation. The treatment of each reactant may be carried out by conventional process. |