Abstract: Metal magnetic memory testing technology is a novel method which can early detect stress concentration level of ferromagnetic components, but the influence of initial magnetization state on magnetic memory signal is extremely complicated. On theoretical analysis, based on law of approach and theoretical formula, that the change law of the stress-induced magnetization is explained is a process which initial magnetization state is constantly close to anhysteretic magnetization state altered with the stress changing. To verify the theoretical analysis, a static load tensile test was applied to Q235 steel components with three different initial magnetization states. The experimental result indicates that the initial magnetization state has a crucial effect on the final magnetization state of the member. Therefore, when metal magnetic memory testing technology is used for quantitative detection, the initial magnetization state of the component can not be ignored.