Abstract: The technique of wind tunnel free-flight test for multi-bodies separation, a more complicated wind tunnel special test technique, has been developed. With this new technique, the multi-bodies separation process of the aircraft can be simulated more accurately, and the whole separation process can be recorded by the high-speed camera. The technique is introduced in detail, include the principle, characteristic, test model design, similarity criteria, and test apparatus. Based on the different characteristic and application fields, the technique of wind tunnel free-flight test for multi-bodies separation can be classified as stage separation, submunition separating from dispenser and multi-bodies separation with additional constraints. Detailed specification is given for each type. The test images and flight path curves of each separated-body are presented. According to the above presentation, the technique of wind tunnel free-flight test for multi-bodies separation, can be well understand and easily adopted by more researchers engaged in wind tunnel test.