Abstract: Advanced research on air-breathing engine development requires sensitive tech-niques to monitor the temperature distribution in the engine,gas flow fields distribution in the combustion reactant and product concentrations to validate combustion theoretical models and in the engine designs.Moreover,the real time acquisition of these parameters can be utilized to con-trol the working status of the engine to optimize the combustion efficiency.Because of its com-pactness,high sensitivity,fast response and non-intruding measurement feature,the tunable di-ode laser absorption spectroscopy (TDLAS )has been applied by many research institutes in tough in-flight environment,such as high temperature,high speed and violent vibration.In this paper,some electronic key techniques in the hypersonic research program HIFiRE are introduced and our design on compact sensors and some progresses are presented.It has been proved that this system can work stably in in-situ measurement and the compact design (volume of 30×15× 10cm3 ,mass<5kg,power<10W)can provide a reference for the in-flight system in the future.