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5%, 10% and 15%Yb-doped SrCeO₃-base proton conducting ceramic tubes were prepared by solid reaction. The Electromotive forces (EMF) were continuously detected by the hydrogen probes which were fabricated with the tubes in molten aluminum at 750℃. Hydrogen contents were calculated as a result. Synthesis and pressed process parameters of ceramic tubes were discussed. The effect of Yb-doped amount and assembly methods, air chamber length or bottom thickness of the probes on the response time, sensitivity, accuracy, reproducibility and impedance spectrum characteristics for the hydrogen sensors were studied. The results indicated that the mixed powders were formed purer proton conductor after calcining at 1400°C for 4 hours. The relative density of the tubes can be improved at higher pressure (275MPa) or more holding pressure time (3-6min). The response time of the sensor can be reduced to 2-4 min by using probes which had more Yb doped amount, less tube wall thickness or shorter gas compartment length with inverted U-shaped sealing method. The reference gas flow or pressure had a rapid, outstanding and reversible effect on the EMF. It is necessary to measure and control the reference gas flow or pressure for acquiring the accurate hydrogen content.