Abstract: Amplified Source Method(ASM) is based on point kinetics model. While used in Accelerator Driven System(ADS) with deep subcriticality and strong external source, its result is affected by the external source effect, the fundamental flux effect and the spatial effect seriously. In order to solve this problem, an annular detector positioning method with calibration has been given. In order to test the practicality of this method, further study is performed against the Kyoto University Critical Assembly by Super Monte Carlo Program for Nuclear and Radiation Simulation(SuperMC) with the HENDL database. Numerical results demonstrate that the proposed method works well for the problem and the six fission chambers in the assembly can give a good measurement result. And more detectors arranged on the fringes of the core are needed in the upcoming experiments to get more accurate measurement results.