In order to fully understand the consequences of the interaction of electric and thermal fields

a time-domain finite element（FE） equation and an FE equation were derived for describing such electric and thermal fields based on the variational principle.Two comprehensive finite element calculation codes were compiled for electric field and thermal field

respectively.The validity of the FE code for time-domain electric field was verified by comparing the simulation results with the predictions of a commercial package

named integrated engineering software（IES）.The thermal FE code was validated by analytical solution of temperature distribution in a coaxial cable.A comparison of the electric field and thermal field distributions in cable terminals equipped with linear

nonlinear

or composite structural stress control tubes（SCT） was presented.The results reveal that a uniform electric field distribution is achievable by selecting appropriate structure and material for cable terminals

and significant reduction in terminal loss and temperature elevation is found in cable terminals by employing nonlinear SCT.And it is of great practical significance for cold-shrinkable terminal design.