As an essential part of many structures in engineering applications, the influence of fin is necessary. For this reason, studies on temperature fields and thermal properties of fin are essential. In the paper, based on the nonlinear temperature-dependent material, exact solutions for temperature distribution, heat transfer rate, efficiency, and effectiveness of fin are obtained by comprehensively considering different thermal influence parameters. In addition, a three-dimensional solid fin model is established by ABAQUS software, and the secondary development of the HETVAL subroutine is carried out with the help of the FORTRAN language. The numerical simulation results, in some cases, are intuitively shown and compared with the theoretical results. This study provides a comprehensive theoretical basis for future experimental studies, numerical simulation analysis, and engineering practice of fins with different materials.