The invention provides a system and method for testing mechanical properties of a conductor material at a high-temperature vacuum environment. According to the system and the method, the problems that the high-temperature strain is difficult to test, the sample heating efficiency is low, and the like are solved. The system comprises a high-temperature strain test subsystem, a temperature control subsystem and a loading subsystem; and a stretch process is carried out in a vacuum environmental chamber, and a sample is loaded by virtue of a mechanical test machine. According to the method, a Joule effect is adopted, a material is put into the vacuum environmental chamber, the normal temperature absolute vacuum degree can reach 0.025Pa, low voltage and high current are introduced to the conductor material so as to rapidly heat the sample, the loading is carried out after reaching a target temperature, meanwhile, data collection is carried out on a high-temperature deformation field by virtue of a DIC strain test technique so as to obtain a strain field of a whole sample scale distance section and a displacement-load curve of the sample, and subsequent processing is carried out so as to obtain high-temperature tensile/compression modulus and tensile strength of the sample. The system and the method have the advantages of high heating speed, uniform temperature field, high deformation measurement precision and the like.