The information of the gravity field and gravity gradient reflects the geological information of the Earth's interior. The cold atom interferometer using laser-induced stimulated Raman transitions is one of the most sensitive methods for measuring the gravity and gravity gradient. In order to restrain the noises, one can use two sets of cold atom gravimeters working simultaneously in a system. The common-mode noise in such a system was investigated in detail in this paper. The research on the restraint of the common-mode noise mainly included vibration noise restraint. Moreover, the authors used the ellipse fitting to analyze the common-mode noise and found that the vibration noise can be mostly canceled out in this system.