The every element of influencing timing jitter performance of dispersion-managed soliton(DMS) system is studied.Through analysis in theory,it is clear that the accumulated dispersion of dispersion management,the additional accumulated dispersion and the map strength of dispersion management are the key elements to the timing jitter performance of DMS system.Lower average dispersion and higher map strength can reduce timing jitter.Additional accumulated dispersion has important influence on timing jitter.When it is equal to one half of the overall accumulated dispersion of dispersion management,timing jitter is reduced most.The numerical calculation result validates the analysis in theory.The conclusion received is helpful to improve the timing jitter performance of DMS system.