A mid-infrared carbon monoxide (CO) gas detection system based on vir tual lock phase amplification technology is implemented by using the powerful data processing capabilities of personal computer and LabVIEW platform.In this paper,a dual-channel pyroelectric detector is used to detect the gas concentration,a universal serial bus (USB) data acquisition card is used to sample the sensing signal,a nd a virtual lock-in amplifier,which is constructed by the multipliers,filters and direct current amplitude ex traction module of LabVIEW,is used to derive the amplitude of the sensing signal.By using standard sine-wave sign als with tunable amplitudes as the signals to be measured,the amplitudes of the output signals from the fabricated lock-in amplifier and the standard amplitudes are both tested and compared,and the linear fitting factor is up to 99.978%.Gas calibration experiments are carried out using the detection system and the prepared 20CO g as samples,and the accuracy, stability and detection limit of the system are measured.Experimental results sh ow that the detection limit is about 50×10－6,the relative detection errors on the 20gas samples are less tha n 4.2%,and the three-hour long-term detection on the 3500×10－6 CO gas samples indicates a variation range of ±6%.Due to rich resources and scalable functions of LabVIEW,this system shows superior advantages in gas dete ction under laboratory environment as compared with the detection system based on embedded micropr ocessor.