Abstract: To study the polarized conversion characteristics of vertical cavity surface emitting lasers (VCSEL), frequency-induced polarization switching (PS) and polarization bistability (PB) of 1550nm VCSEL subject to orthogonal optical injection were investigated numerically by adopting extended spin-flip model. The results show that under orthogonal optical injection, PS and PB can be achieved through varying the frequency detuning between the injected field and the x linearly polarized mode in VCSEL consecutively. Furthermore, the variation of injection power and bias current have strong effects on PB width and VCSEL output emission. The controlling of frequency-induced PS and PB in a 1550nm VCSEL can be realized with appropriate selection of operating conditions. This study has reference value for the application of VCSEL in all-optical switching and all-optical memory.