Gas sensors based on liquid crystals constitute an emerging research field. Due to the chemical diversity, reversible molecular arrangement, and inherent self-assembly capabilities of liquid crystals, they can satisfy the characteristics of high sensitivity, rapid response, low energy consumption, and selectivity in sensors. As related research advances, methods for liquid crystal gas sensing continue to be refined. This paper reviews recent years' liquid crystal-based gas sensing technology and discusses the existing methods for gas detection using liquid crystals, mainly including nematic liquid crystal gas detection methods and cholesteric liquid crystal gas sensing methods. Nematic liquid crystal gas sensing includes functionalized substrate liquid crystal film sensing, geometrically tailored liquid crystal sensing, and liquid crystal droplet sensing methods. Cholesteric liquid crystal gas sensing mainly includes gas sensing with polymer cholesteric liquid crystal films,liquid crystal droplet sensing,gas detection based on optical fibers, and cellulose gas sensing. Finally, the application and development of liquid crystal gas sensing are discussed.