For researching the surface integrity formation of AerMet100 ultrahigh strength steel during grinding with single alundum wheel, the grinding temperature field was studied from the macro- and micro-viewpoint by means of experiments and numerical simulation. First, the constitutive model of AerMet100 was established by tests, and then an experiment for measuring grinding force and temperature was carried out. Based on the results, the grinding thermal load acting on grinding surface was determined. Finally, two kinds of FEA numerical simulation were finished. One was to simulate the macro temperature distribution in grinding zone, and another was to simulate the micro temperature field near the contact zone between grain and workpiece. Results show that the maximum temperature in macro grinding temperature field ranges from 190 ℃ to 500 ℃, and that in micro temperature field can be up to 820 ℃. The influence depth of micro grinding temperature field is 5 μm to 10 μm.