The development of high-power space electric propulsion technology has a very urgent requirement of LaB6 cathode material with low work function. In this paper, rare earth Ce was selected as doping element to reduce work function of LaB6. Firstly, La1-xCexB6 solid solution nanopowders（x=0.2, 0.4, 0.6, 0.8）were prepared by a molten salt route, and then they were used as raw materials to fabricate La1-xCexB6 cathode materials by hot pressing sintering. XRD and SEM technology were used to investigate microstructures of La1-xCexB6 cathode materials. The effect of Ce doping on work function of LaB6 cathode material was studied. Results show that the La1-xCexB6 cathode materials fabricated by hot pressing sintering of La1-xCexB6 nanopowders are single phase solid solution, their relative densities range from 98.49%~98.98%. The work functions of La1-xCexB6 cathode materials are between 1.85 eV and 2.54 eV, all lower than that of LaB6 without Ce doping. Besides, work function of La1-xCexB6 cathode materials decreases at first and then increases with Ce content increasing. La0.6Ce0.4B6 cathode material has the lowest work function of 1.85 eV. Solid solution doping of rare earth Ce is an effective way to reduce work function of LaB6 cathode material.