Thermal modal testing plays an important role in the aerospace engineering. However, excitation approaches applied in tests at room temperature do not work well in thermal environments. This paper, to solve this problem, introduces the impact series excitation approach to excite the structures by the modal shaker. Two excitation configurations are presented for the tests under different temperature conditions. Compared with the conventional shaker excitation, this approach shows apparent advantages thanks to the avoidance of mechanical connection between the shaker and the test article. As both excitation configurations can yield high-quality test results in different temperature environments, the proposed approach is validated to be effective and convenient to modal testing.