CsI scintillant is divided into CsI(TL),CsI(Na) and CsI, threekinds:The CsITLcrystal which is activated by Tl doesn''t deliquatein the air and easily processed into flake, so it is widely appliedto the exploration of energy spectrum,while CsI( Na) deliquateseasily and needs sealing.They have common characteristics of bigdensity and high average atomic number, so they have higherexploration efficient to r-ray and x-ray, which is 40% higher thanNaITLcrystal; CsI crystal has no cleavage surface, soft, but hascertain plasticity, so the crystal can be made into variousprobers, at the same time, they can resist various strong impact,vibration and big thermograde,while not hurt. Our company canproduce various CsI crystals with the heat-resistant temperaturesof 150.C,175.C,200.C.