The electrical resistance of the fused interface is simply characterized using a resistive layer, and the voltage distribution inside the vertical-cavity surface-emitting lasers(VCSELs) are calculated by using a method of finding self-consistent solutions for the Poisson′s, injected current density, carrier diffusion, and voltage drop equations, and the temperature distribution inside the VCSELs are obtained subsequently by solving the thermal conduction equation. The influences of the electrical resistance of the fused interface on the distribution of voltage and temperature inside the single-fused VCSELs and the radial distribution of the injected current density, carrier density, voltage drop and temperature in the active layer are analyzed in detail.