Abstract: In the ordinary way, the output performance of ⁸⁵Kr radioactive source depends on activity, 85Kr radioactive sources with equal activity have similar output performance. But the output performance of ⁸⁵Kr thickness gauge source on the market is inconsistent while the sources have the same size and activity, and this may be related to the preparation process of ⁸⁵Kr radioactive source by different suppliers. Furthermore, preparation process that shell material, active region and feed gas should be considered. ⁸⁵Kr radioactive source with equal activity (7.4 GBq) were prepared by different shell material, active region and feed gas with different abundances. The output voltage of these ⁸⁵Kr radioactive sources were measured by ⁸⁵Kr β output voltage device developed by HTA Co., Ltd. The results show that ⁸⁵Kr radioactive source prepared by titanium shell has lager output voltage than stainless shell, ⁸⁵Kr radioactive source prepared by small activity region has a little bit lager output voltage than big activity region, and output voltage of ⁸⁵Kr radioactive source prepared by more abundant feed gas is slightly lager than less abundant feed gas. This because that ⁸⁵Kr radioactive source prepared by titanium shell, small activity region and lager abundant feed gas has less absorption of beta rays than that prepared by stainless shell, big activity region and less abundant feed gas. This can guidance on of preparation for ⁸⁵Kr thickness gauge source based on β output efficiency.