System level accelerated demonstration tests design considering dispersion of accelerated factor synthesizes traditional risk deriving from life distribution of batch products and risk in model selection. The key is to find the equivalent dispersion of accelerated factor on system level from accelerated factor dispersion of components, life distribution of components and structure of system. In other words, based on system structure, with information of components, we have synthesized the risk from life distribution and model selection. With the help of dispersion of accelerated factors, we can design verification testing for system with one sample and make a comprehensive assessment of system reliability with multiple samples. There are several advantage of proposed approach: 1, we can verify the life of products considering its scatter factor with only one sample, which cannot be achieved with traditional framework; 2, we can estimate the lower confidence limit of products life with a small sample size; 3, the risk of model selection is considered in test design.