A new system of concentration measurement of carbon monoxide is presented. Based on the spectrum ab-sorp tion theory, double-beam detection technology is used. Near-infrared light source and detector are chosen in the system. Compared to traditionalmid2infrared apparatus, the total cost of these devices can be cut down. Op tical fiber can be used to transmit near-infrared op tical signal instead of traditional comp lex system, then the structure would become miniaturization. The princip le and the main specification of the technology will be introduced in the article.