Electromagnetic anti-fouling technology (EAFT) is applied to treat scale in cooling water systems and conductivity, pH and particle diameter in solution are the main performance parameters which can reflect the effect of EAFT. In this paper, a series of experiments are carried out to analyze the change rules of the three parameters in solution, both with and without an EAFT device. The motion law of charged particles in the electromagnetic field is analysed, the electromagnetic anti-fouling technology can accelerate collision and the precipitation of scale ions in solution. The experimental results showed electromagnetic anti-fouling technology can effectively reduce the conductivity and pH in solution, and increase the average particle diameter in solution. The main experimental results are listed as follows: (1) With EAFT, conductivity and pH in solution decrease obviously after 4 hours of circulation, and both of them decrease rapidly in the first hour of the experiment, meanwhile the average particle diameter in solution increases quickly; (2) Under four groups of experiments, conductivity and pH in solution drop as the sweep frequency is lower, but the average particle diameter in solution increases.