To enhance the detection of alkane gas concentrations across a broad spectrum, this study introduces a mid-infrared telemetry and remote sensing approach utilizing the Cassegrain system. The design of the optical system's transmitting, receiving, and detecting modules was explored. Utilizing a 3 464 nm mid-infrared light source in conjunction with the Cassegrain system, an optical system for alkane concentration telemetry and remote sensing was developed. To accommodate target measurements within a 25-100 m range, an optical telemetry system was crafted with a 25 cm diameter. To counteract optical signal loss in the Cassegrain system, a transmission aspheric collimation structure was employed, enabling target focusing at varying distances. To address issues arising from the system's large aperture, a co-axial transmission and reception strategy, reducing disparity were implemented. The system can accurately measure targets within the 25-100 m range. Both primary and secondary mirrors were coated with a mid-infrared enhanced gold film, significantly boosting system stability. Testing reveals the system's overall transmission efficiency at 86%, with a reception efficiency of 75.8%. This alkane telemetry and remote sensing system facilitates remote gas concentration measurement over extensive ranges and distances, offering convenience, rapid measurement, and enhanced field safety. It ensures the optical system's stability and operational safety.