By adding the nonlinear medium in the cavity, the supercontinuum laser is produced by the resonant cavity directly. The problem of the traditional super continuous spectrum laser source demanding the high power and multi stage amplification structure is avoided. In the cavity, using the acoustic optical modulator (AOM) as the Q medium, the pulse is divided under the influence of the modulation instability, and the supercontinuum laser with average output power of 102 mW is obtained directly, with the corresponding optical-optical efficiency of 5%. In addition, the spectral range is from 440 nm to 1700 nm, with 10 dB flatness of 500 nm.