The thermal behaviors of the elliptical microcavity laser are analyzed experimentally and theoretically. The major axis of the elliptical microdisk is 12 μm, the minor axis is 10 μm, and the output waveguide with width of 2 μm is connected directly. The thermal characteristics are investigated based on the lasing characteristics for continuous-wave electrical injection operations. The mode wavelength shift is used to estimate the temperature impedance (Z_T=0.846 K/mW) during continuous operation. Based on the finite- element modeling, the thermal impedance is simulated for the elliptical microcavity laser and the simulation results are in good agreement with the experimental data. The maximum temperature impedance deviation between the simulated and experimental results is about 5%. The temperature rise in the active region as a function of the substrate size is investigated. The simulated results indicate that the heating performance of the benzocyclobutene-confined elliptical microcavity laser can be greatly improved by using an interlayer thermal shunt.