To improve the reliability and operation life of metallic Bi targets for the production of medical isotope ²¹¹At using high current α beam, several beam uniformization methods were simulated and compared. The thermal effect of 500 eμA α beam bombarding a Bi target with wobbler magnet was modeled and analyzed by computational fluid dynamics (CFD) method, which provided key technical support for the design of target system and the improvement of target life time. The results showed that the peak beam thermal effect on the target was obviously reduced by applying beam scanning. In front of the target, a wobbler magnet was used to periodically scan the beam, which could effectively reduce the temperature on Bi target surface. With a scanning frequency of 50 Hz, the highest temperature on Bi target was 189.8 ℃, lower than the melting point of Bi metal (271.3 ℃), which could meet the temperature requirement of Bi target under such a high beam power condition.