The invention provides a large-scale multifunctional corrosion stimulation test rack taking a test circular road as a main part, which is used for simulating the corrosion condition of high acid natural gas containing H2S, CO2 and Cl on a pipeline parent metal and a welded joint under the pipeline transmission condition. The device and the method provided by the invention can be applied to pipeline parent bodies with different pipe diameters, materials, steel grades and wall thicknesses, or a welded joint corrosion test; and test functions such as test on corrosion of the pipe section parent metal and the welded joint, sulfide stress cracking (SSC), hydrogen induced cracking (HIC), washout, corrosion inhibitor effect, welding process evaluation, corrosion monitoring method comparison, pipeline-corrosion-preventing process optimization and the like are integrated into a whole; and the test functions, such as preference of the corrosion process in the pipeline are integrated into a whole, thus reasonable material selection and safe welding quality are guaranteed, and the corrosion condition of the corresponding corrosion condition on the welded joint and the parent metal is known.