In order to improve the cooling capacity of the converter valve phase change dispersion for converter valve cooling system are prepared with phase change materials(CrodaThermTM 47 and CrodaThermTM 53), emulsifiers(BrijTM S2 and Sympatens AS-100), nucleating agents(Polyvinyl alcohol) and deionized water as raw materials. The effects of different factors such as formulation and preparation technology of phase change dispersion on the properties of phase change dispersion are studied by experimental method. The best formulation (based on the total mass of phase change emulsion, the mass fractions of phase change material, emulsifier, nucleating agent and deionized water are 16%, 1.6%, 2.4% and 80% respectively) and shear process (shear rate 50 ks -1, lasting time 5 min) are determined. The convective heat transfer coefficient, conductivity, voltage stability and compatibility with cooling system are analyzed. The results show that the apparent specific heat capacity of the new phase change dispersion is 50% higher than that of deionized water, and the heat transfer capacity is 100% higher than that of deionized water. The key performance of the new phase change dispersion such as electroconductibility, insulation and withstand voltage parameters can meet the cooling application requirements of the converter valve.