Finite Element Method Of Lines is used in the analysis of thermal field in this paper. Using axisymmetric element, the application of Finite Element Method Of Lines in the analysis of thermal field is illustrated. This paper presents the theoretical derivation for the application of Finite Element Method Of Lines, and obtains the ordinary differential equations and corresponding boundary conditions. High quality ordinary differential equations solver is selected to solve the ordinary differential equations. The temperature of an arbitrary point can be obtained by calling subroutine APPSLN.