The invention discloses a process method for treating thiram sodium cobalt slag. The method comprises the following steps that (1) acid washing and zinc removing are carried out; (2) roasting is carried out; (3) water leaching is carried out; (4) extracting and purifying are carried out; (5), ammonium oxalate precipitating is carried out, and (6) cobalt oxalate calcining is carried out, wherein the roasting process comprises the steps that 10 wt%-30 wt% of sodium persulfate is added into acid washed slag obtained by acid washing and zinc removing, and then the mixture is heated for secondary roasting after being subjected to primary roasting. The method has the beneficial effects that most of zinc can be recycled by low-pressure acid washing in the acid washing process, high-temperature pressurizing leaching and other strengthening means are not needed, so that the equipment investment and the production cost are reduced; and sodium sulfate is used as a roasting additive, so oxygen generated during decomposing is used for providing an enhanced oxidizing atmosphere for thermal decomposition, the generated sodium sulfate is used for replacing common concentrated sulfuric acid, so that the generation of acid mist is reduced, a compact oxidation film formed on the surface layer of an ore grain can be destroyed, so that cobalt oxide on an inner layer is continued to be in contact with O2, SO2 and SO3, complete sulfating is achieved, and the recycling rate of cobalt is improved.