A multi-wavelength laser and a wavelength control method are disclosed. The multi-wavelength laser includes a waveguide, a first electrode, and a second electrode. The first electrode and the second electrode are disposed on the waveguide. The first electrode is electrically isolated from the second electrode. The first electrode includes a plurality of sub-electrodes, and every two adjacent sub-electrodes are electrically isolated. The second electrode is configured to amplify an optical signal in the waveguide by loading a current. At least one sub-electrode is configured to adjust a wavelength of the optical signal in the waveguide by loading a current or a voltage.