The invention relates to a complex brass composite steel plate uncombined area repair welding method. A welding method of inert gas welding is adopted; inert gas adopts mixed gas of argon and helium, so that the arc heat effect is improved, the preheating temperature of a complex brass composite steel plate can be lowered, the heat efficiency is improved, and the labor intensity of operators is reduced; compared with pure helium, the inert gas reduces the production cost to a certain extent; a transition layer is welded between complex brass and a basic layer steel plate for effectively preventing adverse effect on composite layer welding line metal by components of the basic layer steel plate to guarantee the joint quality and performance; and Al and Si elements in a welding material selected by the transition layer and a cover surface layer can inhibit evaporation of zinc in the complex brass, so that the health of operators is guaranteed when guaranteeing the performance of the complex brass.