Abstract: The pipe flow test device in early phase had many shortcomings in power, test process, pressure measurement and flow rate control. The paper reviews the develop ment and improvement process for the pipe flow test device. The process of restart for gelled crude oil in pipe is very complicated due to the thermal and shear history, the thixotropy property, the viscoelasticity and the compressibility of crude, the shrinkage caused by depression of temperature and the wave speed in pipes and so on. The correlated theory on the restart process for gelled crude oil is summarized and the thixotropy models are discussed.