The invention belongs to the technical field of metallurgy through a Ni-Co wet process and particularly relates to a comprehensive utilization method for iron-aluminum slag. The method comprises the following steps: carrying out selective leaching to the iron-aluminum slag and dissolving to release nickel, Co and aluminum in the slag; then adding sodium sulfide into a nickel, cobalt and aluminum leach liquor, precipitating and recycling nickel and cobalt in a solution to obtain an aluminum sulfate coarse liquor; adding an oxidizing agent and sodium hydroxide into the aluminum sulfate coarse liquor to remove iron therein, then adding sodium sulfate salt in a supplementing manner, and preparing the solution into a stock solution for producing sodium aluminum sulfate; and evaporating the stock solution and crystallizing to obtain a sodium aluminum sulfate product . According to the comprehensive utilization method provided by the invention, by processing hazardous solid waste iron-aluminum slag, not only can high-valence Ni-Co metal be recycled, but also aluminum therein can be used for producing high value sodium aluminum sulfate, and the method has the advantages that the process is simple and easy to operate, the cost is low, while economic benefits are obtained, environmental pollution factors are eliminated, and excellent social benefits are obtained.