To systematic study the factors which influence the braking torque in liquid-cooled eddy current retarder with a structure of two salient poles, we analyze the related theory of electromagnetics and the formulas for the braking torque of eddy current retarder (ECR) were deduced on the basis of the working principle of liquid-cooled ECR with a structure of two salient poles. And the braking system model was built, the electrical conductivity and magnetic permeability of materials, the excitation current and the rotor speed on retarder braking torque have been studied by JMAG software. The theoretical and finite element analysis was verified and the general regularity of the influence factors of braking torque in liquid-cooled ECR was obtained through the prototype test.