Considering that heavy metal elements possess the characteristic of highenergy radiation shielding, chemical sludge containing 10%(by mass) barium was used as raw material. Meanwhile, kaolin and analytically pure chemicals were supplemented as correction materials. Through optimization design of the mix proportion of raw material, the functional aggregate with low heavy metal release rate and excellent performance of radiation shielding was prepared in proper calcination system. The results show that, the functional aggregate bulk density reaches 2.95×103kg/m3, water absorption is as low as 1.57%, compressive strength is as high as 82MPa, barium ion leaching rate is 1mg/L, and the linear attenuation coefficient is as low as 0.2439cm-1. Therefore, the functional aggregate is expected to be able to replace barite ore in the radiation shielding concrete.