There are many ways to limit the current flowing in the vertical-cavity surface-emitting laser (VCSEL), in which the preparation technology of oxide aperture (current injection aperture) confining method is simple. So the oxide aperture confining method becomes a universal choice. The simulation result shows that the maximum current density is at the edge of the oxide aperture for the oxide aperture confined VCSEL. The influence of the inner radius of the P-type electrode on the current density of the injection aperture is also simulated. The results show that when the inner radius of the P-type electrode increases, the current density at the edge of the device oxide aperture increases, the corresponding device working voltage increases, and the output optical power declines. The device surface spot area is calculated with optical field distribution and divergence angle distribution of the device structure comprehensively considered. The optimal inner radius of the P-type electrode is 8 μｍ.