Abstract: Aiming at the research on relationships between the train axle box parameters,the definition of top-down design,boundary conditions,performance index and design parameters are given.By using the method of House of Quality (HoQ) theory and complex network theory,the main parameters in boundary conditions from higher values of out-degree index of the spring species,weight,vehicle suspension and other parameters are gained.Car-body weight,free vibration,primary suspension and other parameters which have higher values of out-in-degree index is the most considerable performance indexes.And the damper cylinder volume,material,spring center horizontal span and other parameters which have higher values of in-degree index are the main design parameters.The main design parameters can be obtained based on the uniform definition of index formula for out degree and in degree.

Key words: top-down design, axle box parameters relationships, House of Quality(HoQ), complex network