Aircraft stall-spin problem is always focused by aircraft designers during the design phase. So far, several methods can be used to investigate aircraft stall-spin problem, such as CFD analysis, wind tunnel tests, scaled model free flight tests. Aircraft spin research is commonly carried out in spin tunnel, and two techniques, free-spin test and rotary balance test can be chosen. The principle of these two tests are different, but aircraft spin characteristics can be obtained from these two tests in different point of view. This paper clearly presents these two tests, include principle and test process. The example comparison shows that the test results are supplementary to each other.