Portable combustible gas detector with intrinsic safety ( detector hereinafter ) , which continuously monitors combustible gas concentration, is applied for explosion-proof, toxic gas leak detection, rescue, and also applied in the surroundings such as underground pipe and mine, to keep the workers safe from invasion of the toxic, deleterious gas and avoid damage to equipment.The detector inspects combustible gas by natural diffusion and adopts importedcatalytic combustion sensor, having good sensibility and excellent repeatability. The device has embedded micro control technique and Chinese user menu, making the operation easy.  The cover of the detector is refined from high-intensive engineering material (compound elastic rubber), which made the detector touches well, waterproof and explosion-protection.