Abstract: In the perspective of systematology, it is a complex system to solve the problem of system of systems (SoS) combat test. The concept and connotation of SoS were studied based on the basic theory of complex system, and a typical example of SoS was illustrated. On the basis of the demonstration and trait of complex system of SoS combat and SoS combat test, the complexity of SoS combat test was analyzed on two important items including non-linearity and emergency. Through analyzing the basic traits of custom performance test method, it was summarized that performance test method cannot adapt to SoS combat test from these traits, and the fundamental cause was that the reductionism did not adapt to the complexity of SoS combat test. The deficiency of performance test method was analyzed on methodology emphatically under the condition of SoS combat. Aiming at the deficiency of the performance test method on methodology, it was concluded that the methodology should be studied from the perspective of complex system in order to adapt to SoS combat test.