A method of numerical material testing is developed for evaluating the macroscopic yield strength of steel products after cold working process. The method is realized by the micro-macro decoupled analyses based on the crystal plasticity homogenization method. A unit cell for micro-scale analyses, which is composed of several grains, is regarded as a numerical specimen in this method. After validating the method of decoupled nonlinear homogenization, we devise a stepwise procedure for evaluating the yield strength of steel pipes subjected to cold-working. First, we perform a numerical simulation of a Pilger mill rolling process for a steel pipe. Second, the obtained macroscopic deformation history is applied to the unit cell to obtain the numerical specimens after the forming process. Then, numerical material tests are conducted on the specimens to characterize the anisotropy in macroscopic yield strengths and their results are compared with the experimental data.