The digital image processing(DIP) technology was used in Zeeman effect to analyze fringe patterns.The novel methods of determining non-uniform fringe peak by edge detection and measuring circle radii by tangent location by mouse are proposed.A real-time processing CCD system and practical software have been established.The result shows that the DIP system can mensurate the ratio of charge to mass of electron expediently and can greatly highten the accuracy by more than one order of magnitude compared with photograph method.