This system uses micro-flow gas thermal conductive sensor TCS208F for hydrogen volume fraction detection.The signal conditioning circuit and environment temperature control circuit in the external of the sensor are designed in order to achieve constant temperature detection.The weak signal outputed by the sensor is sent off through the measuring bridge.It is primarily amplified by the integrated chip AD708

secondary and amplified by the subtraction circuit.Finally the standard voltage signal is carried into the measurement system of MCU C8051F020 for following-up treatment to complete the hydrogen volume fraction detection.Theoretical study and experimental results show that the detector overcomes many difficult problems of the traditional thermal conductive sensor such as large error detection

environmental temperature compensation and so on

it has broad application prospects.