Abstract: A preparation method of small particle-sized polybutadiene latex used for the production of ABS is disclosed, which includes putting components comprising 34.00-45.00% by weight of the butadiene, 0-6.0% by weight of the second monomer, 52.11-63.13% by weight of the desalinized water, 0.12-0.22% by weight of the mercaptan(TDM), 0.80-2.60% by weight of the emulsifiers composed of potassium abietate and potassium oleate, into the same polymerization reactor, then heating the mixture of the components and stirring the same at a temperature range of 60-75° C. The reaction lasts for 9-12 hours and the conversion is higher than 97%. The method has the advantages such as higher conversion, shorter reaction period and lower latex viscosity. During the first stage of the reaction, more heat is released by increasing the reaction rate. When the conversion reaches 40-80%, the heat release rate of intermediate stage is depressed by decreasing the reaction temperature.