A model of 34 degrees of freedom for two-axle bogie locomotive has been studied in three respects: lateral stability, dynamic response to random track irregularities and non-linear curving performance. The effects of various parameters, in particular the influence of the primary yaw stiffness Kψ, are investigated. This paper is aimed at presenting the most reasonable parameters of prototype electric locomotive design. After comparing the criteria of dynamics in all respects, it has been recommended that two sets of Kψ value may be taken in designing a passenger or freight service prototype respectively.