Tunable diode laser absorption spectroscopy (TDLAS) is a new method to detect target gas concentration, based on the wavelength tunable characteristic of diode laser, by obtaining the absorption spectra in the characteristic absorption region. Autobalanced detection based on TDLAS can effectively eliminate laser intensity noise and other common mode noise. The experiment shows that autobalanced detection could obtain ideal result. The detection limit is below volume ratio 1.2×10-6, and the precision is improved by one order of magnitude contrast to the direct absorption spectroscopy. This autobalanced detection method gains absorption spectra directly, and without signal modulation and lock-in amplifiers, so the excess laser noise is avoided. The noise-cancelling circuit is simple, and it could reduce the cost and system fit volume, and make the system apt to integrate.