A helical long-period grating (HLPG) was written in a polarization maintaining fiber (PMF) with CO2 laser. The twist characteristics of individual and cascaded PMF-HLPG were investigated experimentally. It was found that PMF-HLPG behaved differently with a different light input. When a polarized light was launched into the cascaded PMF-HLPGs with opposite helical direction, a high twist sensitivity of 0.8 nm/rad/m could be achieved in a narrow twist rate range of 0–8 rad/m. The proposed PMF-HLPG would have a promising prospect for the application of the twist monitor.