The noise characteristics of vertical cavity surface emitting laser (VCSEL) are analysed by using rate equations with a reasonable noise simulating method,and the effect of device parameters (such as spontaneous emission factor,output power,injection current and threshold current) on relative intensity noise,frequency noise and spectral linewidth is calculated under single-mode condition.The results are in agreement with experiments.These results may be helpful for optimising the structure design and determing the factors in the application of VCSEL.