Carbon dioxide, the major constituent of the atmosphere and burnt gas, has great significance in high sensitive detection in physics and chemistry as well as in the life sciences applications. The existing CO2 detection methods have some defects, which makes the detection difficult to meet the need of the national defense scientific research, energy and chemicals as well as the clinical human breath analysis. Quartz-enhanced photoacoustic spectroscopy (QEPAS) technology invented lately has the advantages of high selectivity, compactness and immunity to environmental acoustic noise. Based on the fact that the QEPAS detection sensitivity scales linearly with excitation laser power, a power boosted QEPAS sensor for CO2 detection is developed. The sensor is based on QEPAS with an erbium-doped fiber amplified 1 572 nm distributed feedback (DFB) laser. In order to reduce the sensor background noise to the thermal noise of the quartz tuning fork, wavelength modulation spectroscopy and the harmonic detection technique were employed. In order to optimize the sensor performance, the laser wavelength modulation depth was optimized at normal atmosphere. A 3.5 ppm detection limit was obtained in the condition of 1 495 mW laser power, 0.33 cm-1 modulation depth and 0.833 Hzdetection bandwidth. The corresponding normalized noise equivalent absorption coefficient was 1.01×10-8 W·cm-1·Hz-1/2.