Abstract: The high temperature proton conductor solid electrolyte Ba3Ca1+xNb2-xO9-δ exhibit good chemical stability and high conductivity, so it has a good application prospect. Ba3Ca1+xNb2-xO9-δ (x=0, 0.10, 0.18, 0.30) composite perovskite oxides were prepared by solid state synthesis. With the increase of Ca-doped content, the conductivity of Ba3Ca1+xNb2-xO9-δsample first increased and then decreased, the conductivity of x=0.18 sample was the highest. The electron hole transport number of Ba3Ca1+xNb2-xO9-δis low in the atmosphere containing hydrogen. When the temperature is lower than 750°C, the proton conduction of Ba3Ca1+xNb2-xO9-δ is dominant. When the temperature reaches 800°C, the oxygen ions in Ba3Ca1+xNb2-xO9-δ are mainly conduction carriers. The proton transport number of Ba3Ca1+xNb2-xO9-δ with Ca doping x=0.10 was the highest. With the increase of dopant amount, the oxygen ion transport number of Ba3Ca1+xNb2-xO9-δ increased gradually, while the proton transport number decreased gradually.