Abstract: Composite insulators are important component for EAST Tokamak magnet system, and the insulators are needed to insulate all cryogenic supply lines which are on ground potential from the high voltage potential of winding. The insulators have to withstand the hydraulic pressure and high voltage during all operation modes. Keeping mechanical integrity of the component under operation conditions is the most important. For safe reason, an overall check and analysis of cryogenic mechanics property for EAST Tokamak composite insulators is needed. The theoretical analysis of cryogenic mechanics property for EAST Tokamak composite insulators was carried out，and the result by the way of experiment was validated. Based on this， the damage causes of the insulators were also analyzed.