A scheme of all-optical wavelength converter based on the gain saturation effect in a double-wavelength laser diode with fiber grating external cavity is presented.The feature of the scheme is that the input signal can be converted to two wavelengths of the laser diode by using the wavelength convert- er.The gain saturation effects of optical injection at 1 554.8 nm on output power at 1 531.5 nm and 1 549.4 nm are observed,which shows that input optical signal can be converted to two wavelengths of the double-wavelength laser diode simultaneously.