Abstract: For the purpose of realizing the all-fiber gas detection system with high sensor sensitivity, using the Hollow Core-Photonic Crystal Fiber (HC-PCF) as gas cell, a dual-optical path differential near-infrared carbon dioxide detection experimental system based on virtual instruments LabVIEW and the absorption spectroscopy around wavelength 1 572.48 nm of carbon dioxide molecule was developed. The system response time was about 100 s by inflating the HC-PCF of 1.8 m long from two ends under the pressure of 0.1 MPa. The detection system was calibrated with carbon dioxide of standard concentration. Carbon dioxide with known concentration of 2%, 5%, 10% and 100% were tested respectively and the experimental results showed that the detection errors relative to standard concentration were no more than 2% and the maximum standard deviation of measured concentration were 3.32% in 100 minutes. In addition, the optical path of gas absorption reaches 1.8 m and the system detection sensitivity of 5.981 810-5 W/ppm was achieved.