Threshold current characteristics of intracavity-contacted oxide-confined vertical-cavity surfaceemitting laser had been investigated in detail. Threshold current characteristics not only were depended on the size of oxide-aperture, but also were also strongly affected by the mismatch of its lasing mode and gain peak.For the same degree detuning of the gain peak and lasing mode at room temperature, the threshold current was approximately proportional to the square of the oxide-aperture diameter of above 5 μm. For the same oxideaperture device, the larger the detuning degree of the lasing mode shifted to the shorter wavelength of the gain peak at room temperature was, the lower the minimum threshold current was. The wavelengths of the lasing mode and gain peak were ±N× 10 nm detuning at 300 K, The temperature of the minimum threshold current was changed to be about ± N × 40 K (N real number). The calculated results were consistent with the experimental ones.