In order to analyze the feasibility of using magnetic memory testing technology to pipeline online inspection,it’s necessary to consider the effect of pressure on the pipeline defects magnetic memory signals. Based on the J-A force-magnetic coupling model a relationship between the relative permeability and stress was concluded. The relationship was imported in ANSYS software to carry out the co-simulation between mechanical and static magnetic. The results show that magnetic memory signals of defects have two characteristics—— radial magnetic field in the pipeline mutating from minimum to maximum and axial magnetic field appearing maximum. The magnetic field inside the pipeline decreases and defect’s magnetic memory signals decreases and then remains constant when the pressure increases. Magnetic memory testing technology can be used in pipeline online inspection.