GB/T 20969.4-2008 "Special environmental conditions plateau machinery, part 4: plateau natural environment test guidelines, internal combustion power machinery", for the plateau environment of internal combustion power machinery, to provide natural environment test guidance. The standard specifies the purpose of the test, the scope of application, under the unique low pressure, anoxia, temperature difference and other environment conditions of the plateau, the test items, methods, procedures and evaluation criteria of internal combustion power machinery, to help test its adaptability and Reliability in the plateau environment.