A laser system and a laser outputting method are disclosed. The method comprises: providing a oscillator, wherein the oscillator comprises a pump light source, a cavity and a mode locked controller; utilizing the pump light source to emit a pump light into the cavity; outputting first laser pulses to the spectrum converter; utilizing a wavelength conversion chip of the spectrum converter to convert the first laser pulses to second laser pulses; utilizing at least one photo-detector to detect a power of the second laser pulses; controlling the mode locked controller to modulate a mode-locked status of the cavity when the power of the second laser pulses is lower than a threshold value.