Accurate detection of nitric oxide （NO） is crucial for applications in environmental， biomedical， and other fields. NO demonstrates strong absorption in the mid-infrared wavelength range， enabling high-sensitivity detection using tunable diode laser absorption spectroscopy （TDLAS） with a mid-infrared quantum cascade laser as the light source. This study develops a three-stage thermoelectric cooler （TEC）-based temperature control structure， introduces a concentration inversion model， and enhances detection sensitivity through optimized laser temperature stability and gas concentration inversion. Experimental results reveal rapid stabilization of laser temperature at room temperature with a stability of 0.003 ℃. The proposed model outperforms the 2f/1f model under identical conditions. Utilizing the signal's peak-to-peak value for concentration inversion over a 30 m optical path and with three-stage laser temperature control， the system achieves an NO concentration measurement linearity of 0.997 5 and a detection limit of 37.5×10^-9 within a 0-500×10^-6 range. By optimizing both laser temperature control and the inversion model， the NO detection sensitivity is improved by two orders of magnitude.