On basis of two-phase flow and the heat transfer theory, the velocity and temperature of the liquid lend-bismuth eutectic were calculated with gas-injection and without gas-injection by FLUENT code, in the calculation segment. The radial velocity profiles and temperature profiles were acquired at different cross section. Analysis results show that: no matter the argon is existence or not, the velocity distribution and the temperature distribution have a good symmetry. Temperature rise of the liquid lend-bismuth eutectic with gas injected is larger than without argon. It is shown that the gas-injection is good for heat transfer of liquid lend-bismuth in the calculation segment.