Abstract: The hydrate ice plugging which affects the gas transportation flow often occur in the pipeline during the CO₂ gas transportation at Yanchang oilfield. In order to explore the formation law of CO₂ hydrate, the phase equilibrium curve of CO₂ hydrate is generated by PVTSIM software. The hydrate formation law in horizontal section and bend section of pipe is simulated by OLGA software. The results show that at low temperature and high pressure, hydrate formation occurs in horizontal section and bend section of pipe. The formation process is a kind of salt-like crystallization, which usually includes two stages of nucleation and growth, and then relies on the adhesion force between fluid particles to cause hydrate aggregation. Compared with the straight section of pipe, it is found that the bend section of pipe is easier to produce hydrate. The hydrate formation rate is from low to high, then quickly enters the stable stage, and finally tends to 0. And the hydrate also occuring at the bend section of pipe in field further verifies the formation law of CO₂ hydrate in this paper. Therefore, in the process of pipeline transportation, the conditions of high pressure outlet and low temperature inlet are avoided to ensure the safe operation of pipeline.