Thermal conductivity is one of the most important physical properties of thin films. Different from two- or three-dimensional measurement structures in most reports, in this work, one-dimensional (1D) two-end supported cantilever beam is provided. The structure of cantilever includes a metal heater (which also serves as a thermometer) and thin film(s) underneath for measurement. 1D heat flow equation is employed to obtain the expression of temperature rise distribution (T(x)) along the cantilever beam and voltage drop changes along the heater (U) when a direct current (DC) follows in the heater. To confirm the correctness of theoretical deduction, ANSYS finite element software is employed to simulate T(x) and U. Results demonstrate that the simulations are in good agreement with the theoretic calculations obtained from expressions of T(x) and U. Compared with conventional 3-times frequency (3 ) method, the DC method with 1D cantilever beam is relatively simple and accurate.