Abstract: The experiments for testing photic stability of the seed source core, the analysis of the surface composition, the estimation for uniformity of dose distributing of the seed source core, the research on self-shield effect of the seed source core, and the investigation for welding seed source core were carried on. The results show that the photic stability of the seed source core prepared by plating palladium is better, ¹²⁵I distributes on basic material by physical adsorption evenly, and the self-shield coefficient is about 64%. The parameters of welding seed source core by laser weld were confirmed.