In order to study and develop forging technology for polymers, cold compression tests for atactic PMMA was done with upsetting deformation by using three kinds of deformation rates and four kinds of deformation degrees. In the tests, atactic PMMA′s brittle behavior in the tensile deformation could be improved and some plastic-alike behavior (or solid state formability) could be attained by upsetting deformation. Meanwhile, the tendency appeared after cold compressing that elastic recover decreased with the increase of deformation rate, but too large elastic recover could make upsetting not be applied in polymers forging. Through analyzing test results, it will be necessary that cold  deformation is changed to hot-forming + cold treating or high speed forming, etc. in order that polymer forging technology may be used in industrial manufacturing.