La0.8Ce0.2(Fe11.5-xCox)Si1.5(x=0、0.3、0.5、0.7) ribbons were prepared by melt spinning. The phases and the magnetic property were characterized by X-ray diffraction and a vibrating sample magnetometer. The results show that Co and high quenched-speed help form the NaZn13-type phase. The substitution of Fe by Co can enhance the Curie temperature. The maximum magnetic entropy changes and the magnetic hysteresis decrease because of the substitution of Fe by Co. However, the magnetic hysteresis increases with quenched-speed rising. The quenched-speeds have little effect on maximum magnetic entropy changes and the Curie temperature.