A method of mode tracking based on modal participation factor (MPF) is developed and integrated into topology optimization of head suspension assemblies (HSAs). This method is devised to track the lowest torsional and the lowest sway frequencies, which are maximized as design goals for suspension assembly. Topology optimization based on this method is successfully used to find optimum designs for maximum torsional frequency, maximum sway frequency, or maximum both goals. The resulting topology images are then interpreted and reduced into physical form with three thickness levels among which reduced thickness helps improve the lowest torsional frequency.