Samarium and neodymium co-doped ceria (Ce0.8Sm0.1Nd0.1O2-δ or SNDC) and apatite-type lanthanum silicate (La10Si6O27or LSO) powders were prepared by citric-nitrate self-combustion and Sol-gel method respectively.Composite materials were obtained by mixing two powders at different proportion.Powders were molded into shaps and isostatic cool pressed, then sintering at different temperature (1500℃,1550℃,1600℃) for 10 hours. Samples were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), and electrical conductivity measurement. What we can know from the results is that no impurity phase exists in SNDC/LSO composites, and the grain size decreases with the addition of LSO. High sintering temperature can help to improve the conductivity of 30wt%LSO sample, moreover, the addition of LSO reduced the conductivity of composite electrolytes which sintered at 1500℃.