The synthesis of thioamides and thiolactams, which are used as important organic intermediates, has attracted great attention. However, expensive reagents, severe reaction conditions and low yields of the target products made conventional methods inconvenient and economically infeasible. To overcome these disadvantages, we investigated a new process for synthesizing thioamides and thiolactams. We examined thermal reactions of CS2 with Nmethyl-2-pyrrolidinone, formylamide, acetamide and N, N-dimethylformylamide, respectively. The results show that under optimum conditions N-methylpyrrolidine-2-thione and the corresponding thioamides can be obtained in good to excellent yields by the above thionation reactions.