In view of the transient heat conduction problem of radiator structure, firstly, based on the thermodynamic theory, the integral equation of the problem can be derived through the governing equation of the problem. Then, for the domain integral in the integral equation, the dual reciprocal boundary element method (DRBEM) is used to obtain the boundary integral equation. Then the boundary is discretized to obtain the constant coefficient differential equations. Finally, the precise integration method (PIM) is used to solve the equations, thus obtaining the temperature results of the internal points. Based on the comparative analysis of the results between the boundary element method and the finite element method calculation software workbench, the results show that the boundary element method is characterized with the advantages of small amount of calculation but a high accuracy, which verifies the high accuracy of the coupling solution of DRBEM and PIM as an alternative and effective numerical calculation method for solving transient heat transfer problems.