Abstract-The characteristics of guided modes in the four-layer slab waveguide containing chiral nihility core have been investigated theoretically.The characteristic equation of guided modes is derived. The dispersion curves, energy flux and normalized power of guided modes for three cases of chiral metamaterial parameters are presented. Some abnormal features are found, such as the existence of fundamental mode and surface wave mode, unusual dispersion curves, positive energy flux in the chiral nihility core, and zero power at some normalized frequencies.