Aimed at the unreliable sealing problem of packer rubber with non normal distribution variables in the engineering practice,a mechanical reliability model of packer rubber was established,and a numerical analysis method of mechanical reliability sensitivity of Edgeworth series and fourthorder moment was proposed.The reliability sensitivity of the random variables of the sealant cylinder was compared and analyzed,and the influence of the change of the structural parameter design on the reliability of packer rubber was obtained.The results show that the influence of the physical dimension of normal distribution is more significant on the reliability of the packer than the working pressure difference and the sealing load of nonnormal distribution.In nonnormal random variables,the influence of working pressure difference on the sealing reliability of packers rubber is greater than that of sealing load.With the increase of the random variance sensitivity,the packer rubber tends to be unreliable,but the variation of the variance sensitivity of different structural variables has different effects on the reliability of the packer rubber seal.The validity and accuracy of the method were verified by designing the reliability sensitivity of the packer rubber.This method can be used as a basis for quantitative design of reliability evaluation indexes and structural parameters of packer rubber in engineering application.