The invention belongs to the technical field of detection and relates to a portable laser carbon dioxide detection device applicable to agriculturalplanting and breeding environment. The portable laser carbon dioxide detection device comprises a vertical cavity surface emitting laser (VCSEL), wherein the VCSEL emits laser and is connected with an optical power splitter via a mono-mode optical fiber; one path output by the optical power splitter is connected with a self-focusing collimating lens via the mono-mode optical fiber; signals sent by the self-focusing collimating lens are received by a first photoelectric detector; the self-focusing collimating lens, the first photoelectric detector and a quartz plate are located in tested gas atmospheresimultaneously; the other path output by the optical power splitter is connected with a second photoelectric detector via the mono-mode optical fiber; the second photoelectric detector and the first photoelectric detector are same in type; the first photoelectric detector and the second photoelectric detector are successively connected with an analog-to-digital converter and a single-chip microcontroller; the single-chip microcontroller is connected with a light crystal display (LCD) display screen. Compared with the common laser gas detector, the power consumption of the portable laser carbon dioxide detection device is obviously reduced; the portable laser carbon dioxide detection device is more applicable to portable equipment.