The start-up of two-phase UASB reactor (Ke et al., 2005) designed for experiment is investigated in this paper, so as to seek the rapid start-up method. Glucose and starch are used as the organic-carbon source of the synthetic wastewater in the experiment (Show et al., 2004). Starting up at low organic loading, the influent COD is increased quickly and HRT is shortened by stages, so that acidogenic phase can work in acidic optimal condition as soon as quickly. After 36 days of operation, 69% of total bioparticles are more than 1.0mm, and most of the granular diameter is between 2mm and 3mm in acidogenic reactor. So acidogenic phase achieves rapid start-up successfully (Ren et al., 2005).