Abstract: For the mechanism of wax and scale control in magnetic treatment, theory of electricity and statistical mechanics as well as mathematic analysis are made use of to study charge distribution around the colloidal particles in electrolyte, calculation is done to the effect of magnetic field on this kind of charge with the formula given on the effect of magnetic field on the charge distribution around colloidal particles under the circumstances of high temperature and dilute solution. The writer holds such an opinion that there is a layer of ionic charge around the colloidal particles in the electrolyte, the thickness of the charge depends on temperature and particle concentration. When the concentration of the particles increases, the thickness of ion layer gets thinner, but the concentration takes place among the colloidal particles; When the temperature increases, the particle layer becomes thicker, thus preventing colloidal particles from concentrating among themselves. Magnetic field can make the ion layer thickness change when the colloidal particles in electrolyte are located outside of the magnetic field. When both colloidal particles and ions are of paramagnetism/diamagnetism, the ion layer gets thinner, which is advantageous for the particles to concentrate among themselves. When ions and particles are of different magnetisms, the ion layer gets thicker, which is disadvantageous for colloidal particles to concentrate and the higher strength of magnetic field is, the bigger the charge of ion layer thickness will be.