The shrinkage and creep of high strength concrete was affected by the mixed fly ash. The influence was directly related to the long-term behavior of structures. The shrinkage and creep experiment of C50 concrete with fly ash content 0, 12%, 24% were conducted with 100 mm×100 mm×400 mm prism specimens in the laboratory. Four kinds of current commonly used specifications for the shrinkage and creep of high strength concrete were assessed. With the experiment results and other existing research referenced, the fly ash influence coefficient and its correction model were introduced to reflect the influence of different load age and fly ash content. The analysis showed that the shrinkage and creep mode recommended from JTG D62 and GL 2000 agreed well with the measured results form the reference specimens. And the verification conclusion demonstrated that the introduced fly ash influence coefficient could be applied to the shrinkage and creep of high strength concrete with fly ash.