Abstract: Link bandwidth is a basic metric for network performance analysis and capacity planning and optimization The commonly used method for link bandwidth measurement is VPS（variable packet size） with limitation of precision affected by deviation accumulation and cross traffic An improved bandwidth measurement method based on VPS named PTVS（packet train with variable size） is proposed for random link PTVS can elminate infections of deviation accumulation caused by hop-by-hop measurement and cross traffic It is shown that PTVS has merits of precision, high efficiency and speed from measurement on operated network The other metrics offered by PTVS include RTT, one-way delay, packet loss rate, end-to-end bottleneck bandwidth, and utilization of link